How many commands are in the database?

The explorer covers 200+ essential Linux commands across file management, networking, system administration, and text processing.

What is the best command to find files?

The find command is the most powerful tool for searching files by name, size, or modification date. For a simpler, faster search by name, use the locate command.

How do I check my server's memory?

You can use the free -h command to see available and used RAM in a human-readable format, or htop for a real-time interactive dashboard.

What command changes file permissions?

The chmod command is used to change file permissions. We also offer a dedicated File Permission Calculator tool to help you generate the correct chmod command.

How do I safely shut down a Linux server?

Use the sudo shutdown -h now command to halt the system immediately and safely. This ensures all processes are terminated properly.

What does the grep command do?

The grep command searches through text files for specific patterns or words. It is incredibly useful for finding errors inside massive server log files.

How do I compress files in Linux?

The tar -czvf archive.tar.gz /folder command is the standard way to combine multiple files into an archive and compress them using gzip.

sudo stands for "Superuser Do". Placing it before a command executes that command with administrative (root) privileges, which is required for installing software or modifying system files.

How do I see my IP address in the terminal?

Typing ip a or ip addr show will display all network interfaces and their assigned IP addresses. The older ifconfig command also works on many systems.

Can I use these commands on macOS?

Yes! Because macOS is built on a Unix foundation, the vast majority of standard terminal commands (like ls, cd, grep, and tar) work exactly the same way as they do on Linux.

Linux Command Explorer — Search Linux Commands & Examples

ls

List information about files and directories in the current working directory or specified locations.

File Management

Syntax

ls [OPTION]... [FILE]...

Common Options

Option	Description
`-l`	Use a long listing format
`-a`	Do not ignore entries starting with .
`-h`	Print sizes in human readable format (e.g., 1K 234M 2G)
`-R`	List subdirectories recursively
`-t`	Sort by modification time (newest first)
`-r`	Reverse order while sorting

Examples

List all files including hidden ones with detailed information

$ ls -la

List files in /var/log with human-readable file sizes

$ ls -lh /var/log

cd

Change the current working directory to the specified path.

File Management

Syntax

cd [DIRECTORY]

Common Options

Option	Description
`~`	Change to home directory
`..`	Change to parent directory
`-`	Change to previous directory

Examples

Change to home directory

$ cd ~

Change to parent directory

$ cd ..

pwd

Print the full pathname of the current working directory.

File Management

Syntax

pwd [OPTION]

Common Options

Option	Description
`-P`	Display physical path without symlinks
`-L`	Display logical path with symlinks

Examples

Display current working directory

$ pwd

mkdir

Create new directory or directories.

File Management

Syntax

mkdir [OPTION]... DIRECTORY...

Common Options

Option	Description
`-p`	Create parent directories as needed
`-v`	Print a message for each created directory
`-m`	Set file mode/permissions

Examples

Create a directory

$ mkdir new_folder

Create nested directories

$ mkdir -p parent/child/grandchild

rmdir

Remove empty directories.

File Management

Syntax

rmdir [OPTION]... DIRECTORY...

Common Options

Option	Description
`-p`	Remove parent directories when empty
`-v`	Print a message for each removed directory

Examples

Remove an empty directory

$ rmdir empty_folder

touch

Change file timestamps or create an empty file.

File Management

Syntax

touch [OPTION]... FILE...

Common Options

Option	Description
`-c`	Do not create any files
`-a`	Change only the access time
`-m`	Change only the modification time
`-t`	Use specified timestamp

Examples

Create a new empty file

$ touch file.txt

Update modification time of existing file

$ touch file.txt

cp

Copy files and directories from source to destination.

File Management

Syntax

cp [OPTION]... SOURCE... DESTINATION

Common Options

Option	Description
`-r/-R`	Copy directories recursively
`-i`	Prompt before overwriting
`-u`	Copy only newer files
`-p`	Preserve attributes (permissions, timestamps)

Examples

Copy a file

$ cp file1.txt file2.txt

Copy directory recursively

$ cp -r /source /destination

mv

Move or rename files and directories.

File Management

Syntax

mv [OPTION]... SOURCE... DESTINATION

Common Options

Option	Description
`-i`	Prompt before overwriting
`-u`	Move only newer files
`-n`	Do not overwrite existing files
`-v`	Explain what is being done

Examples

Rename a file

$ mv oldname.txt newname.txt

Move file to different directory

$ mv file.txt /home/user/documents/

rm

Remove files or directories from the system.

File Management

Syntax

rm [OPTION]... FILE...

Common Options

Option	Description
`-r/-R`	Remove directories recursively
`-f`	Force removal without prompting
`-i`	Prompt before every removal
`-v`	Explain what is being done

Examples

Remove a file

$ rm file.txt

Remove directory recursively (careful!)

$ rm -rf directory/

ln

Create hard or symbolic links between files.

File Management

Syntax

ln [OPTION]... TARGET LINK_NAME

Common Options

Option	Description
`-s`	Create symbolic (soft) link
`-f`	Remove existing destination files
`-n`	Treat destination as normal file
`-v`	Print name of each linked file

Examples

Create symbolic link

$ ln -s /usr/bin/python3 python

Create hard link

$ ln file.txt file_hardlink.txt

cat

Read and output the content of files sequentially.

File Management

Syntax

cat [OPTION]... [FILE]...

Common Options

Option	Description
`-n`	Number output lines
`-b`	Number non-empty output lines
`-E`	Display $ at end of each line
`-s`	Suppress repeated empty lines

Examples

Display file content

$ cat file.txt

Number lines while displaying

$ cat -n file.txt

tac

Display file content in reverse order (last line first).

File Management

Syntax

tac [OPTION]... [FILE]...

Common Options

Option	Description
`-b`	Separate before rather than after
`-r`	Interpret separator as regex
`-s`	Use specified string as separator

Examples

Display file in reverse

$ tac file.txt

nl

Number lines in files with customizable formatting.

File Management

Syntax

nl [OPTION]... [FILE]...

Common Options

Option	Description
`-b`	Number body lines style
`-f`	Number footer lines style
`-h`	Number header lines style
`-n`	Number format (ln, rn, rz)
`-w`	Number width

Examples

Add line numbers to file

$ nl file.txt

head

Display the first lines of files (default: 10 lines).

File Management

Syntax

head [OPTION]... [FILE]...

Common Options

Option	Description
`-n`	Number of lines to display
`-c`	Number of bytes to display
`-q`	Never print headers
`-v`	Always print headers

Examples

Show first 20 lines of file

$ head -n 20 file.txt

tail

Display the last lines of files (default: 10 lines).

File Management

Syntax

tail [OPTION]... [FILE]...

Common Options

Option	Description
`-n`	Number of lines to display
`-f`	Follow file growth (stream mode)
`-F`	Follow with file rotation
`-c`	Number of bytes to display

Examples

Show last 20 lines of file

$ tail -n 20 file.txt

Monitor log file in real-time

$ tail -f /var/log/syslog

less

View file contents with pagination and scrolling.

File Management

Syntax

less [OPTION]... [FILE]...

Common Options

Option	Description
`-N`	Show line numbers
`-S`	Chop long lines
`-g`	Highlight search results
`-i`	Case-insensitive search

Examples

View file with pagination

$ less file.txt

more

View file contents page by page.

File Management

Syntax

more [OPTION]... [FILE]...

Common Options

Option	Description
`-d`	Display help prompt
`-c`	Clear screen before display
`-p`	Don't scroll, clean screen
`-n`	Lines per screen

Examples

View file page by page

$ more file.txt

grep

Search files for patterns/regular expressions.

File Management

Syntax

grep [OPTION]... PATTERN [FILE]...

Common Options

Option	Description
`-i`	Ignore case distinctions
`-r`	Recursive search
`-v`	Invert match (exclude)
`-l`	Show only matching files
`-n`	Show line numbers

Examples

Search for text in file

$ grep "error" log.txt

Search recursively in all files

$ grep -r "password" /etc/

egrep

Search using extended regular expressions (equivalent to grep -E).

General

Syntax

egrep [OPTION]... PATTERN [FILE]...

Common Options

Option	Description
`-i`	Ignore case
`-r`	Recursive
`-v`	Invert match
`-w`	Match whole word

Examples

Search with extended regex

$ egrep "(error|warning)" log.txt

fgrep

Search for fixed strings (equivalent to grep -F).

Text Processing

Syntax

fgrep [OPTION]... PATTERN [FILE]...

Common Options

Option	Description
`-i`	Ignore case
`-r`	Recursive
`-v`	Invert match
`-l`	Show only matching files

Examples

Search for literal string

$ fgrep "error*" log.txt

sed

Text stream editor for filtering and transforming text.

Text Processing

Syntax

sed [OPTION]... {script} [input-file]...

Common Options

Option	Description
`-i`	Edit files in-place
`-n`	Suppress automatic printing
`-e`	Add script to commands
`-f`	Use script file

Examples

Replace text in file

$ sed 's/old/new/g' file.txt

Delete lines containing pattern

$ sed '/pattern/d' file.txt

awk

Pattern scanning and processing language for text manipulation.

Networking

Syntax

awk [OPTION]... 'program' [file]...

Common Options

Option	Description
`-F`	Field separator
`-v`	Assign variable
`-f`	Use program file

Examples

Print first column

$ awk '{print $1}' file.txt

Search pattern and print

$ awk '/error/ {print $0}' log.txt

cut

Extract sections/columns from each line of file.

File Management

Syntax

cut [OPTION]... [FILE]...

Common Options

Option	Description
`-c`	Extract by character positions
`-f`	Extract by fields
`-d`	Field delimiter
`--complement`	Output other fields

Examples

Extract first 5 characters

$ cut -c 1-5 file.txt

Extract second field (delimited by comma)

$ cut -d',' -f2 file.csv

paste

Merge lines from multiple files.

File Management

Syntax

paste [OPTION]... [FILE]...

Common Options

Option	Description
`-d`	Delimiter (tab by default)
`-s`	Serial (paste one file at a time)

Examples

Merge two files side by side

$ paste file1.txt file2.txt

sort

Sort lines of text files.

File Management

Syntax

sort [OPTION]... [FILE]...

Common Options

Option	Description
`-n`	Numeric sort
`-r`	Reverse order
`-k`	Sort by key/field
`-u`	Unique (remove duplicates)
`-t`	Field delimiter

Examples

Sort file alphabetically

$ sort file.txt

Sort numerically

$ sort -n numbers.txt

uniq

Report or omit repeated lines (must be sorted).

General

Syntax

uniq [OPTION]... [INPUT [OUTPUT]]

Common Options

Option	Description
`-c`	Count occurrences
`-d`	Only print duplicates
`-i`	Ignore case
`-u`	Only print unique lines

Examples

Display unique lines

$ uniq file.txt

Count duplicate occurrences

$ sort file.txt | uniq -c

wc

Print line, word, and byte/character counts.

Text Processing

Syntax

wc [OPTION]... [FILE]...

Common Options

Option	Description
`-l`	Line count
`-w`	Word count
`-c`	Byte count
`-m`	Character count
`-L`	Longest line length

Examples

Count lines in file

$ wc -l file.txt

Display all counts

$ wc file.txt

tr

Translate or delete characters from input.

General

Syntax

tr [OPTION]... SET1 [SET2]

Common Options

Option	Description
`-d`	Delete characters in SET1
`-s`	Squeeze repeated characters
`-c`	Complement SET1

Examples

Convert uppercase to lowercase

$ tr 'A-Z' 'a-z' < file.txt

Delete specified characters

$ tr -d 'aeiou' < file.txt

tee

Read from stdin and write to stdout and files.

File Management

Syntax

tee [OPTION]... [FILE]...

Common Options

Option	Description
`-a`	Append to files (don't overwrite)
`-i`	Ignore interrupt signals

Examples

Write to file and display output

$ echo "Hello" | tee file.txt

Append to multiple files

$ command | tee -a log1.txt log2.txt

xargs

Build and execute commands from stdin input.

General

Syntax

xargs [OPTION]... [COMMAND] [INITIAL-ARGS]

Common Options

Option	Description
`-n`	Max arguments per command
`-p`	Prompt before executing
`-0`	Items separated by null
`-I`	Replace string

Examples

Delete all .tmp files

$ find . -name "*.tmp" | xargs rm -f

Run commands in parallel

$ echo "cmd1 cmd2" | xargs -n 1 -P 2 sh -c

split

Split file into smaller pieces.

File Management

Syntax

split [OPTION]... [INPUT] [PREFIX]

Common Options

Option	Description
`-b`	Split by bytes
`-l`	Split by number of lines
`-n`	Number of pieces

Examples

Split by lines

$ split -l 1000 bigfile.txt

Split by size

$ split -b 10M largefile.bin

join

Join lines of two files on common field.

File Management

Syntax

join [OPTION]... FILE1 FILE2

Common Options

Option	Description
`-1`	Field in first file
`-2`	Field in second file
`-t`	Field delimiter
`-a`	Include unpairable lines

Examples

Join two CSV files

$ join -t',' file1.csv file2.csv

comm

Compare two sorted files line by line.

File Management

Syntax

comm [OPTION]... FILE1 FILE2

Common Options

Option	Description
`-1`	Suppress column 1 (lines in file1)
`-2`	Suppress column 2 (lines in file2)
`-3`	Suppress column 3 (common lines)

Examples

Show only common lines

$ comm -12 file1.txt file2.txt

diff

Compare files line by line and show differences.

File Management

Syntax

diff [OPTION]... FILES

Common Options

Option	Description
`-u`	Unified format
`-r`	Recursive for directories
`-i`	Ignore case
`-b`	Ignore whitespace

Examples

Compare two files

$ diff file1.txt file2.txt

Unified diff output

$ diff -u file1.txt file2.txt

cmp

Compare files byte by byte.

File Management

Syntax

cmp [OPTION]... FILE1 [FILE2]

Common Options

Option	Description
`-l`	Verbose output
`-s`	Silent (return code only)
`-i`	Skip initial bytes

Examples

Compare two files

$ cmp file1.bin file2.bin

strings

Extract printable strings from binary files.

File Management

Syntax

strings [OPTION]... [FILE]...

Common Options

Option	Description
`-n`	Minimum length
`-a`	Scan entire file
`-t`	Show offset

Examples

Extract strings from binary

$ strings /bin/ls

fmt

Format text by wrapping paragraphs.

Networking

Syntax

fmt [OPTION]... [FILE]...

Common Options

Option	Description
`-w`	Set line width
`-s`	Split only long lines
`-t`	Tab formatting

Examples

Format text to 80 columns

$ fmt -w 80 file.txt

fold

Wrap each input line to fit specified width.

General

Syntax

fold [OPTION]... [FILE]...

Common Options

Option	Description
`-w`	Set line width (default 80)
`-s`	Break at spaces

Examples

Fold lines to 50 characters

$ fold -w 50 file.txt

rev

Reverse characters in each line of file.

File Management

Syntax

rev [OPTION]... [FILE]...

Examples

Reverse each line

$ rev file.txt

shuf

Randomly permute lines from input.

General

Syntax

shuf [OPTION]... [FILE]

Common Options

Option	Description
`-n`	Number of output lines
`-o`	Output to file
`-r`	Repeat output

Examples

Shuffle lines randomly

$ shuf file.txt

Generate random numbers

$ shuf -i 1-100 -n 5

seq

Print sequence of numbers.

Text Processing

Syntax

seq [OPTION]... LAST
seq [OPTION]... FIRST LAST
seq [OPTION]... FIRST INCREMENT LAST

Common Options

Option	Description
`-f`	Format string
`-s`	Separator
`-w`	Equal width with leading zeros

Examples

Generate sequence 1 to 10

$ seq 10

Generate with format

$ seq -f "0%g" 5

yes

Output a string repeatedly (default: 'y').

Text Processing

Syntax

yes [STRING]...

Common Options

Option	Description
`--version`	Display version
`--help`	Display help

Examples

Automatically confirm yes

$ yes | command

Output custom string repeatedly

$ yes "Hello World"

printf

Format and print data (C-like printf).

Text Processing

Syntax

printf FORMAT [ARGUMENT]...

Common Options

Option	Description
`-v`	Assign to variable
`-f`	Include file

Examples

Print formatted text

$ printf "Hello %s\n" "World"

Format with padding

$ printf "%10d\n" 123

echo

Display line of text/string to stdout.

Text Processing

Syntax

echo [OPTION]... [STRING]...

Common Options

Option	Description
`-n`	Do not output trailing newline
`-e`	Enable escape sequences
`-E`	Disable escape sequences

Examples

Print simple text

$ echo "Hello World"

Enable escape sequences

$ echo -e "Line1\nLine2"

basename

Strip directory prefix from path.

File Management

Syntax

basename [OPTION]... NAME [SUFFIX]

Common Options

Option	Description
`-a`	Support multiple arguments
`-s`	Remove suffix

Examples

Get filename from path

$ basename /home/user/file.txt

Remove extension

$ basename file.txt .txt

dirname

Strip filename suffix from path.

File Management

Syntax

dirname [OPTION]... NAME

Common Options

Option	Description
`-z`	Separate output with null

Examples

Get directory from path

$ dirname /home/user/file.txt

realpath

Print resolved absolute path.

Text Processing

Syntax

realpath [OPTION]... FILE...

Common Options

Option	Description
`-s`	Don't expand symlinks
`-m`	Ignore nonexistent files
`-e`	Require files to exist

Examples

Get absolute path

$ realpath file.txt

readlink

Print value of symbolic link.

Text Processing

Syntax

readlink [OPTION]... FILE

Common Options

Option	Description
`-f`	Canonicalize by following links
`-e`	Canonicalize with existence check

Examples

Read symbolic link

$ readlink /usr/bin/python

file

Determine file type and MIME type.

File Management

Syntax

file [OPTION]... [FILE]...

Common Options

Option	Description
`-b`	Brief output
`-i`	MIME type output
`-z`	Look inside compressed files

Examples

Determine file type

$ file document.pdf

Show MIME type

$ file -i image.png

stat

Display detailed file status/information.

File Management

Syntax

stat [OPTION]... FILE...

Common Options

Option	Description
`-c`	Format string
`-L`	Follow symbolic links
`-f`	Display filesystem info

Examples

Show file statistics

$ stat file.txt

Display only size

$ stat -c %s file.txt

find

Search for files in directory hierarchy.

File Management

Syntax

find [PATH]... [EXPRESSION]

Common Options

Option	Description
`-name`	Match filename pattern
`-type`	Match file type (f,d,l)
`-size`	Match file size
`-mtime`	Match modification time
`-exec`	Execute command on found files

Examples

Find all .txt files

$ find . -name "*.txt"

Find files larger than 10MB

$ find . -size +10M -type f

locate

Find files by name using pre-built database.

File Management

Syntax

locate [OPTION]... PATTERN...

Common Options

Option	Description
`-i`	Ignore case
`-l`	Limit results
`-r`	Use regex pattern
`-c`	Count results

Examples

Find file by name

$ locate file.txt

Case-insensitive search

$ locate -i document

updatedb

Update the locate database.

General

Syntax

updatedb [OPTION]...

Common Options

Option	Description
`-o`	Output database file
`-e`	Directories to exclude
`-U`	Root path

Examples

Update database (as root)

$ sudo updatedb

which

Show full path of shell command.

User Management

Syntax

which [OPTION]... COMMAND...

Common Options

Option	Description
`-a`	Show all matches
`-s`	Silent (only return code)

Examples

Find command location

$ which python

Show all matches

$ which -a python

whereis

Locate binary, source, and man pages.

General

Syntax

whereis [OPTION]... COMMAND...

Common Options

Option	Description
`-b`	Search only binaries
`-m`	Search only man pages
`-s`	Search only sources

Examples

Find all occurrences

$ whereis ls

Search only binary

$ whereis -b gcc

type

Display command type (alias, function, built-in, file).

File Management

Syntax

type [OPTION]... NAME...

Common Options

Option	Description
`-a`	Display all locations
`-t`	Print type only
`-p`	Print path of file command

Examples

Show command type

$ type ls

Show all locations

$ type -a python

whatis

Display one-line description of command.

Networking

Syntax

whatis [OPTION]... KEYWORD...

Common Options

Option	Description
`-r`	Interpret as regex
`-w`	Wildcard matching

Examples

Get command description

$ whatis ls

apropos

Search man pages for keyword.

General

Syntax

apropos [OPTION]... KEYWORD...

Common Options

Option	Description
`-a`	Match all keywords
`-e`	Exact match
`-r`	Regex match

Examples

Search for print-related commands

$ apropos print

man

Display system manual pages.

System Admin

Syntax

man [OPTION]... [SECTION] COMMAND

Common Options

Option	Description
`-k`	Keyword search
`-f`	Whatis (short description)
`-a`	Show all matches
`-w`	Show location of man page

Examples

View manual for ls

$ man ls

Search for commands

$ man -k grep

info

Read GNU Info documentation.

General

Syntax

info [OPTION]... [TOPIC]

Common Options

Option	Description
`-f`	Specify file
`-n`	Go to node
`-a`	Show all matches

Examples

View info for coreutils

$ info coreutils

help

Display help for shell built-in commands.

User Management

Syntax

help [OPTION]... [COMMAND]

Common Options

Option	Description
`-m`	Display in man format
`-s`	Short description

Examples

Get help for cd

$ help cd

chmod

Change file/directory permissions.

File Management

Syntax

chmod [OPTION]... MODE... FILE...

Common Options

Option	Description
`-R`	Recursive
`-v`	Verbose output
`-c`	Changed files only
`--reference`	Copy permissions

Examples

Make file executable

$ chmod +x script.sh

Set permissions (rw-r--r--)

$ chmod 644 file.txt

chown

Change file owner and group.

File Management

Syntax

chown [OPTION]... [OWNER][:[GROUP]] FILE...

Common Options

Option	Description
`-R`	Recursive
`-v`	Verbose output
`--from`	Change only if current owner/group matches

Examples

Change file owner

$ chown user file.txt

Change owner and group

$ chown user:group file.txt

chgrp

Change file group ownership.

File Management

Syntax

chgrp [OPTION]... GROUP FILE...

Common Options

Option	Description
`-R`	Recursive
`-v`	Verbose output
`--referece`	Copy group from reference

Examples

Change file group

$ chgrp staff file.txt

umask

Set default file creation permissions mask.

File Management

Syntax

umask [OPTION]... [MASK]

Common Options

Option	Description
`-p`	Print umask in symbolic format
`-S`	Print umask in symbolic format

Examples

Display current umask

$ umask

Set new umask

$ umask 022

install

Copy files and set attributes (like cp but with permissions).

File Management

Syntax

install [OPTION]... SOURCE... DESTINATION

Common Options

Option	Description
`-d`	Create directories
`-m`	Set permissions
`-o`	Set owner
`-g`	Set group

Examples

Install file with permissions

$ install -m 755 script.sh /usr/local/bin/

Create directory

$ install -d /custom/path

mktemp

Create temporary file or directory.

File Management

Syntax

mktemp [OPTION]... [TEMPLATE]

Common Options

Option	Description
`-d`	Create directory
`-p`	Use specific directory
`-t`	Use template

Examples

Create temporary file

$ mktemp

Create with prefix

$ mktemp mytemp.XXXXXX

sync

Write data to disks synchronously.

Disk Usage

Syntax

sync [OPTION]...

Common Options

Option	Description
`-d`	Sync only directory entries
`-f`	Sync filesystem

Examples

Sync all data

$ sync

du

Display disk usage of files and directories.

File Management

Syntax

du [OPTION]... [FILE]...

Common Options

Option	Description
`-h`	Human readable sizes
`-s`	Summarize (total only)
`-a`	Include files
`-c`	Total summary
`-d`	Directory depth

Examples

Show directory size

$ du -sh /home/user

Show top 10 largest

$ du -h / | sort -rh | head -10

df

Display filesystem disk space usage.

File Management

Syntax

df [OPTION]... [FILE]...

Common Options

Option	Description
`-h`	Human readable
`-T`	Show filesystem type
`-i`	Show inodes
`-a`	Include dummy filesystems

Examples

Show disk usage

$ df -h

Show specific filesystem

$ df -hT /dev/sda1

mount

Mount filesystem or view mounted filesystems.

File Management

Syntax

mount [OPTION]... DEVICE DIRECTORY

Common Options

Option	Description
`-t`	Filesystem type
`-o`	Mount options
`-a`	Mount all from fstab
`-r`	Mount read-only

Examples

Mount USB drive

$ mount /dev/sdb1 /mnt/usb

Mount read-only

$ mount -o ro /dev/sda1 /mnt

umount

Unmount filesystem.

File Management

Syntax

umount [OPTION]... DEVICE|DIRECTORY

Common Options

Option	Description
`-l`	Lazy unmount
`-f`	Force unmount
`-r`	Remount read-only if unmount fails

Examples

Unmount device

$ umount /dev/sdb1

Unmount by directory

$ umount /mnt/usb

lsblk

Display list of block devices.

Disk Usage

Syntax

lsblk [OPTION]... [DEVICE]

Common Options

Option	Description
`-f`	Show filesystem info
`-m`	Permissions info
`-l`	List format
`-p`	Full paths

Examples

List all block devices

$ lsblk

Show filesystems

$ lsblk -f

blkid

Display block device attributes and UUID.

Disk Usage

Syntax

blkid [OPTION]... [DEVICE]

Common Options

Option	Description
`-o`	Output format
`-s`	Display specific attribute
`-t`	Search by attribute

Examples

Show all partitions

$ blkid

Get UUID

$ blkid /dev/sda1

fdisk

Manipulate disk partition table.

Networking

Syntax

fdisk [OPTION]... DEVICE

Common Options

Option	Description
`-l`	List partitions
`-u`	Show in sectors
`-s`	Show partition size

Examples

List partitions

$ fdisk -l

Interactive partition editing

$ fdisk /dev/sda

cfdisk

Curses-based partition table manipulator.

Networking

Syntax

cfdisk [OPTION]... DEVICE

Common Options

Option	Description
`-z`	Start with zero partition table
`-P`	Display partition table

Examples

Interactive partition editor

$ cfdisk /dev/sda

sfdisk

Script-oriented partition table manipulator.

Networking

Syntax

sfdisk [OPTION]... DEVICE

Common Options

Option	Description
`-l`	List partitions
`-d`	Dump partition table
`-r`	Read-only

Examples

List partitions

$ sfdisk -l /dev/sda

Dump to file

$ sfdisk -d /dev/sda > backup.txt

parted

Partition manipulation program.

Networking

Syntax

parted [OPTION]... DEVICE [COMMAND]

Common Options

Option	Description
`-s`	Script mode
`-l`	List devices
`-a`	Align option

Examples

List devices

$ parted -l

Create partition

$ parted /dev/sda mkpart primary ext4 0% 100%

partprobe

Inform OS about partition table changes.

Disk Usage

Syntax

partprobe [OPTION]... [DEVICE]

Common Options

Option	Description
`-s`	Show summary
`-d`	Dry run

Examples

Reload partition table

$ partprobe /dev/sda

mkfs

Build a filesystem on a device.

File Management

Syntax

mkfs [OPTION]... DEVICE

Common Options

Option	Description
`-t`	Filesystem type
`-V`	Verbose output

Examples

Create filesystem

$ mkfs -t ext4 /dev/sdb1

mkfs.ext4

Create ext4 filesystem.

File Management

Syntax

mkfs.ext4 [OPTION]... DEVICE

Common Options

Option	Description
`-L`	Volume label
`-b`	Block size
`-m`	Reserved blocks percentage
`-O`	Filesystem features

Examples

Create ext4 filesystem

$ mkfs.ext4 /dev/sdb1

With label

$ mkfs.ext4 -L data /dev/sdb1

mkfs.xfs

Create XFS filesystem.

File Management

Syntax

mkfs.xfs [OPTION]... DEVICE

Common Options

Option	Description
`-f`	Force overwrite
`-L`	Label
`-d`	Data section options
`-l`	Log section options

Examples

Create XFS filesystem

$ mkfs.xfs /dev/sdb1

mkfs.btrfs

Create Btrfs filesystem.

File Management

Syntax

mkfs.btrfs [OPTION]... DEVICE

Common Options

Option	Description
`-L`	Label
`-d`	Data profile
`-m`	Metadata profile
`-f`	Force overwrite

Examples

Create Btrfs filesystem

$ mkfs.btrfs /dev/sdb1

fsck

Check and repair filesystem consistency.

File Management

Syntax

fsck [OPTION]... DEVICE

Common Options

Option	Description
`-t`	Filesystem type
`-A`	Check all filesystems
`-y`	Assume yes to all questions
`-V`	Verbose output

Examples

Check filesystem

$ fsck /dev/sda1

Force check

$ fsck -y /dev/sda1

tune2fs

Adjust ext2/ext3/ext4 filesystem parameters.

File Management

Syntax

tune2fs [OPTION]... DEVICE

Common Options

Option	Description
`-l`	List filesystem features
`-c`	Max mount count between checks
`-i`	Time interval between checks
`-L`	Set volume label

Examples

Set label

$ tune2fs -L data /dev/sda1

Check filesystem parameters

$ tune2fs -l /dev/sda1

e2fsck

Check ext2/ext3/ext4 filesystem.

File Management

Syntax

e2fsck [OPTION]... DEVICE

Common Options

Option	Description
`-p`	Automatic repair
`-f`	Force check
`-c`	Check for bad blocks
`-n`	Read-only check

Examples

Check filesystem

$ e2fsck /dev/sda1

Force check with auto-repair

$ e2fsck -pf /dev/sda1

resize2fs

Resize ext2/ext3/ext4 filesystem.

File Management

Syntax

resize2fs [OPTION]... DEVICE [SIZE]

Common Options

Option	Description
`-p`	Show progress
`-M`	Shrink to minimum size

Examples

Resize to specific size

$ resize2fs /dev/sda1 10G

Expand to all available

$ resize2fs /dev/sda1

xfs_repair

Repair XFS filesystem.

File Management

Syntax

xfs_repair [OPTION]... DEVICE

Common Options

Option	Description
`-n`	Dry run (no changes)
`-d`	Dangerous mode
`-L`	Force log zeroing

Examples

Check filesystem

$ xfs_repair /dev/sda1

Read-only check

$ xfs_repair -n /dev/sda1

btrfs

Btrfs filesystem management tool.

File Management

Syntax

btrfs [SUBCOMMAND] [OPTION]...

Common Options

Option	Description
`subvolume`	Manage subvolumes
`filesystem`	Filesystem operations
`balance`	Balance data
`scrub`	Check data integrity

Examples

Create subvolume

$ btrfs subvolume create /mnt/data

Check filesystem

$ btrfs filesystem show

mkswap

Create swap space on device or file.

File Management

Syntax

mkswap [OPTION]... DEVICE

Common Options

Option	Description
`-f`	Force
`-L`	Label
`-U`	UUID

Examples

Create swap partition

$ mkswap /dev/sda2

swapon

Enable swap space on device/file.

File Management

Syntax

swapon [OPTION]... [DEVICE]

Common Options

Option	Description
`-a`	Enable all from fstab
`-s`	Display summary
`-p`	Set priority

Examples

Enable swap

$ swapon /dev/sda2

Show swap info

$ swapon -s

swapoff

Disable swap space.

Disk Usage

Syntax

swapoff [OPTION]... [DEVICE]

Common Options

Option	Description
`-a`	Disable all swaps
`-v`	Verbose output

Examples

Disable swap

$ swapoff /dev/sda2

free

Display system memory usage.

System Admin

Syntax

free [OPTION]...

Common Options

Option	Description
`-h`	Human readable
`-m`	MB units
`-g`	GB units
`-s`	Continuous refresh
`-t`	Total summary

Examples

Show memory usage

$ free -h

Continuous monitoring

$ free -s 2

vmstat

Report virtual memory statistics.

System Admin

Syntax

vmstat [OPTION]... [DELAY] [COUNT]

Common Options

Option	Description
`-s`	Summary statistics
`-d`	Disk statistics
`-n`	No headers
`-w`	Wide output

Examples

Show memory stats

$ vmstat

Monitor every 2 seconds

$ vmstat 2

iostat

Report CPU and I/O statistics.

System Admin

Syntax

iostat [OPTION]... [DELAY] [COUNT]

Common Options

Option	Description
`-c`	CPU stats only
`-d`	Device stats only
`-x`	Extended stats
`-k`	KB/s output

Examples

Show I/O stats

$ iostat

Monitor every second

$ iostat 1

sar

Collect, report, and save system activity.

System Admin

Syntax

sar [OPTION]... [INTERVAL] [COUNT]

Common Options

Option	Description
`-u`	CPU usage
`-r`	Memory usage
`-n`	Network usage
`-d`	Disk usage

Examples

Show CPU usage

$ sar -u 1 5

Show memory usage

$ sar -r

uptime

Show how long system has been running.

System Admin

Syntax

uptime [OPTION]...

Common Options

Option	Description
`-p`	Pretty format
`-s`	Show since time

Examples

Show system uptime

$ uptime

dmesg

Display kernel ring buffer messages.

System Admin

Syntax

dmesg [OPTION]...

Common Options

Option	Description
`-H`	Human readable
`-T`	Human timestamp
`-f`	Facility
`-l`	Level
`-c`	Clear buffer

Examples

Show kernel messages

$ dmesg | tail -20

Show with timestamps

$ dmesg -T

journalctl

Query systemd journal logs.

System Admin

Syntax

journalctl [OPTION]... [MATCHES]

Common Options

Option	Description
`-f`	Follow logs
`-u`	Unit name
`-p`	Priority level
`-S`	Since date/time
`-e`	Jump to end

Examples

Show all logs

$ journalctl

Follow system logs

$ journalctl -f

Since last boot

$ journalctl -b

hostname

Show or set system hostname.

Networking

Syntax

hostname [OPTION]... [NAME]

Common Options

Option	Description
`-f`	FQDN
`-s`	Short name
`-i`	IP address
`-A`	All addresses

Examples

Show hostname

$ hostname

Set hostname

$ sudo hostname newname

hostnamectl

Control system hostname in systemd.

Networking

Syntax

hostnamectl [OPTION]... [COMMAND]

Common Options

Option	Description
`status`	Show current settings
`set-hostname`	Set hostname
`set-icon-name`	Set icon name
`set-chassis`	Set chassis type

Examples

Show hostname info

$ hostnamectl

Set hostname

$ sudo hostnamectl set-hostname myserver

uname

Print system information.

System Admin

Syntax

uname [OPTION]...

Common Options

Option	Description
`-a`	All information
`-s`	Kernel name
`-n`	Network hostname
`-r`	Kernel release
`-v`	Kernel version
`-m`	Machine architecture

Examples

Show all info

$ uname -a

Show kernel version

$ uname -r

lscpu

Display CPU architecture information.

System Admin

Syntax

lscpu [OPTION]...

Common Options

Option	Description
`-e`	Extended format
`-p`	Parsable format
`-x`	Hex masks

Examples

Show CPU info

$ lscpu

lsusb

List USB devices.

General

Syntax

lsusb [OPTION]...

Common Options

Option	Description
`-v`	Verbose
`-t`	Tree format
`-s`	Specify bus/device

Examples

List USB devices

$ lsusb

Show detailed info

$ lsusb -v

lspci

List PCI devices.

General

Syntax

lspci [OPTION]...

Common Options

Option	Description
`-v`	Verbose
`-nn`	Show numeric IDs
`-k`	Show kernel drivers
`-t`	Tree format

Examples

List PCI devices

$ lspci

Show detailed info

$ lspci -v

dmidecode

Read system hardware data from BIOS.

System Admin

Syntax

dmidecode [OPTION]...

Common Options

Option	Description
`-t`	Type
`-s`	String
`-q`	Quiet mode

Examples

Show all hardware info

$ sudo dmidecode

Show memory info

$ sudo dmidecode -t memory

inxi

Comprehensive system information tool.

System Admin

Syntax

inxi [OPTION]...

Common Options

Option	Description
`-F`	Full output
`-b`	Brief output
`-G`	Graphics info
`-D`	Disk info
`-N`	Network info

Examples

Show full system info

$ inxi -F

Show brief summary

$ inxi -b

neofetch

Display system info with OS logo/ASCII art.

System Admin

Syntax

neofetch [OPTION]...

Common Options

Option	Description
`--off`	Disable ASCII logo
`--image`	Image path
`--color_blocks`	Color blocks
`--disable`	Disable components

Examples

Show system info

$ neofetch

Disable logo

$ neofetch --off

fastfetch

Fast system information display tool.

System Admin

Syntax

fastfetch [OPTION]...

Common Options

Option	Description
`-c`	Config file
`-l`	List presets
`-s`	Structure file

Examples

Show system info

$ fastfetch

screenfetch

Display system info with ASCII art.

System Admin

Syntax

screenfetch [OPTION]...

Common Options

Option	Description
`-v`	Verbose
`-s`	Use screenshot mode
`-n`	No ASCII logo

Examples

Show system info

$ screenfetch

whoami

Print effective username.

Text Processing

Syntax

whoami [OPTION]...

Examples

Show current user

$ whoami

id

Display user and group information.

User Management

Syntax

id [OPTION]... [USER]

Common Options

Option	Description
`-u`	User ID only
`-g`	Group ID only
`-G`	All group IDs
`-n`	Name instead of number

Syntax

who [OPTION]...

Common Options

Option	Description
`-a`	All
`-b`	Boot time
`-r`	Run level
`-q`	Quick summary

Examples

Show logged in users

$ who

Show all info

$ who -a

w

Show who is logged in and their activities.

General

Syntax

w [OPTION]... [USER]

Common Options

Option	Description
`-h`	No header
`-u`	Ignore idle time
`-s`	Short format

Examples

Show users and activities

$ w

last

Show login/reboot history from wtmp.

User Management

Syntax

last [OPTION]... [USER]...

Common Options

Option	Description
`-n`	Number of lines
`-x`	Show system shutdowns
`-f`	Specific file

Examples

Show recent logins

$ last -n 10

lastb

Show failed login attempts.

User Management

Syntax

lastb [OPTION]... [USER]...

Common Options

Option	Description
`-n`	Number of lines
`-f`	Specific file

Examples

Show failed logins

$ lastb -n 10

finger

Display user information.

User Management

Syntax

finger [OPTION]... [USER]...

Common Options

Option	Description
`-l`	Long format
`-s`	Short format
`-p`	No plan file

Examples

Show user info

$ finger username

passwd

Change user password.

User Management

Syntax

passwd [OPTION]... [USER]

Common Options

Option	Description
`-e`	Expire password
`-d`	Delete password
`-l`	Lock account
`-u`	Unlock account

Examples

Change current user password

$ passwd

Change another user's password (root)

$ sudo passwd username

chsh

Change login shell.

User Management

Syntax

chsh [OPTION]... [USER]

Common Options

Option	Description
`-s`	Set shell
`-l`	List valid shells

Examples

Change shell

$ chsh -s /bin/zsh

List available shells

$ chsh -l

chfn

Change user's GECOS/finger information.

User Management

Syntax

chfn [OPTION]... [USER]

Common Options

Option	Description
`-f`	Full name
`-o`	Office
`-p`	Office phone
`-h`	Home phone

Examples

Change user info

$ chfn username

Set full name

$ chfn -f "John Doe" username

su

Run commands as another user.

User Management

Syntax

su [OPTION]... [USER] [ARGUMENT]...

Common Options

Option	Description
`-`	Load environment
`-c`	Run command
`-l`	Login shell
`-s`	Specify shell

Examples

Switch to root

$ su -

Run command as user

$ su - username -c "command"

sudo

Execute commands as another user (typically root).

User Management

Syntax

sudo [OPTION]... COMMAND

Common Options

Option	Description
`-u`	Specify user
`-i`	Login shell
`-s`	Shell
`-l`	List privileges
`-k`	Reset timeout

Examples

Run command as root

$ sudo apt update

Run as specific user

$ sudo -u username command

visudo

Safely edit sudoers file.

File Management

Syntax

visudo [OPTION]...

Common Options

Option	Description
`-c`	Check syntax
`-f`	Specify file
`-s`	Strict mode

Examples

Edit sudoers file

$ sudo visudo

Check syntax

$ sudo visudo -c

login

Begin session on system.

System Admin

Syntax

login [OPTION]... [USER]

Common Options

Option	Description
`-p`	Preserve environment
`-f`	Don't authenticate

Examples

Login as user

$ login username

logout

End login session.

User Management

Syntax

logout [OPTION]...

Examples

Logout from shell

$ logout

env

Set or view environment variables.

General

Syntax

env [OPTION]... [VARIABLE=value]... [COMMAND]

Common Options

Option	Description
`-i`	Ignore environment
`-u`	Remove variable
`-0`	Null termination

Examples

Show environment

$ env

Run command with variable

$ env VAR=value command

printenv

Print environment variables.

Text Processing

Syntax

printenv [OPTION]... [VARIABLE]

Common Options

Option	Description
`-0`	Null termination

Examples

Show all environment

$ printenv

Show specific variable

$ printenv PATH

export

Set and export environment variable.

General

Syntax

export [OPTION]... [VARIABLE[=VALUE]]

Common Options

Option	Description
`-n`	Remove export property
`-p`	Show exported variables

Examples

Set environment variable

$ export PATH=$PATH:/new/path

unset

Remove variable or function.

File Management

Syntax

unset [OPTION]... [VARIABLE]...

Common Options

Option	Description
`-f`	Remove function
`-v`	Remove variable

Examples

Unset environment variable

$ unset VARIABLE

alias

Create or show command aliases.

General

Syntax

alias [OPTION]... [NAME=VALUE]...

Common Options

Option	Description
`-p`	Print all aliases
`-g`	Global alias (zsh)

Examples

Create alias

$ alias ll='ls -la'

Show all aliases

$ alias

unalias

Remove command aliases.

File Management

Syntax

unalias [OPTION]... NAME...

Common Options

Option	Description
`-a`	Remove all aliases

Examples

Remove alias

$ unalias ll

Remove all

$ unalias -a

source

Execute commands from file in current shell.

File Management

Syntax

source [OPTION]... FILE

Examples

Source configuration file

$ source ~/.bashrc

history

Display or manipulate command history.

Networking

Syntax

history [OPTION]...

Common Options

Option	Description
`-c`	Clear history
`-d`	Delete entry
`-w`	Write to file
`-r`	Read from file

Syntax

date [OPTION]... [+FORMAT]

Common Options

Option	Description
`-d`	Display time described by string
`-s`	Set time
`-u`	UTC
`-R`	RFC 2822 format

Examples

Show current date

$ date

Show in specific format

$ date "+%Y-%m-%d %H:%M:%S"

cal

Display calendar.

General

Syntax

cal [OPTION]... [MONTH] [YEAR]

Common Options

Option	Description
`-3`	Show previous/current/next
`-y`	Full year
`-m`	Monday first
`-j`	Julian dates

Examples

Show current month

$ cal

Show specific year

$ cal 2025

timedatectl

Control system time/date in systemd.

System Admin

Syntax

timedatectl [OPTION]... [COMMAND]

Common Options

Option	Description
`status`	Show current settings
`set-time`	Set time
`set-timezone`	Set timezone
`set-ntp`	Enable/disable NTP

Examples

Show current settings

$ timedatectl

Set timezone

$ sudo timedatectl set-timezone UTC

sleep

Delay for specified time.

General

Syntax

sleep [OPTION]... NUMBER[SUFFIX]...

Common Options

Option	Description
`--help`	Display help
`--version`	Version info

Examples

Sleep for 5 seconds

$ sleep 5

Sleep for 1 minute

$ sleep 1m

watch

Execute command periodically.

General

Syntax

watch [OPTION]... COMMAND

Common Options

Option	Description
`-n`	Interval in seconds
`-d`	Highlight changes
`-t`	No header
`-e`	Exit on error

Examples

Watch command every 2 seconds

$ watch -n 2 date

Watch with changes highlighted

$ watch -d ls

time

Time command execution.

General

Syntax

time [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`-o`	Write to file
`-f`	Format string

Examples

Time a command

$ time ls

timeout

Run command with time limit.

General

Syntax

timeout [OPTION]... DURATION COMMAND

Common Options

Option	Description
`-s`	Signal to send
`-k`	Kill after duration

Examples

Run command for 5 seconds

$ timeout 5s ping google.com

nice

Run command with modified niceness.

General

Syntax

nice [OPTION]... [COMMAND] [ARGUMENT]...

Common Options

Option	Description
`-n`	Niceness level (-20 to 19)

Examples

Run with low priority

$ nice -n 10 command

renice

Change priority of running process.

System Admin

Syntax

renice [OPTION]... PRIORITY [PID]...

Common Options

Option	Description
`-n`	Priority level
`-g`	Group
`-u`	User

Examples

Change process priority

$ renice -n 10 -p 1234

nohup

Run command immune to hangup signal.

General

Syntax

nohup [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`-p`	Process ID
`-v`	Verbose output

Examples

Run command in background

$ nohup command &

jobs

Display background jobs in current session.

General

Syntax

jobs [OPTION]...

Common Options

Option	Description
`-l`	Include PID
`-p`	PIDs only
`-r`	Running jobs only
`-s`	Stopped jobs only

Common Options

Option	Description
`-l`	List signals
`-9`	SIGKILL (force)
`-15`	SIGTERM (graceful)

Examples

Terminate process

$ kill 1234

Force terminate

$ kill -9 1234

killall

Kill processes by name.

System Admin

Syntax

killall [OPTION]... NAME...

Common Options

Option	Description
`-9`	SIGKILL
`-u`	Kill user's processes
`-r`	Regex pattern
`-i`	Interactive prompt

Examples

Kill process by name

$ killall firefox

pkill

Kill process by pattern.

System Admin

Syntax

pkill [OPTION]... PATTERN

Common Options

Option	Description
`-f`	Match full command line
`-u`	User
`-t`	Terminal
`-x`	Exact match

Examples

Kill process by pattern

$ pkill firefox

pgrep

Find process by pattern.

System Admin

Syntax

pgrep [OPTION]... PATTERN

Common Options

Option	Description
`-l`	Show process names
`-u`	User
`-f`	Match full command line
`-x`	Exact match

Examples

Find process ID

$ pgrep firefox

ps

Display active processes.

System Admin

Syntax

ps [OPTION]...

Common Options

Option	Description
`-e`	All processes
`-f`	Full format
`-u`	User format
`-aux`	All processes with user

Examples

Show all processes

$ ps aux

Show specific user

$ ps -u username

pstree

Display process tree.

System Admin

Syntax

pstree [OPTION]... [PID|USER]

Common Options

Option	Description
`-p`	Show PIDs
`-u`	Show user names
`-a`	Show command lines
`-h`	Highlight current

Examples

Show process tree

$ pstree

Show with PIDs

$ pstree -p

top

Display dynamic real-time process view.

System Admin

Syntax

top [OPTION]...

Common Options

Option	Description
`-u`	Show specific user
`-p`	Show specific PIDs
`-d`	Refresh interval

Examples

Show processes in real-time

$ top

htop

Interactive process viewer (enhanced top).

System Admin

Syntax

htop [OPTION]...

Common Options

Option	Description
`-u`	Show specific user
`-p`	Show specific PIDs
`-t`	Tree view

Examples

Launch htop

$ htop

btop

Modern, resource monitoring tool with graphs.

General

Syntax

btop [OPTION]...

Common Options

Option	Description
`-t`	Theme
`-c`	Config file

Examples

Launch btop

$ btop

atop

Advanced system and process monitor.

System Admin

Syntax

atop [OPTION]...

Common Options

Option	Description
`-a`	Show all processes
`-c`	Show command line
`-r`	Read from log file

Examples

Launch atop

$ atop

glances

Cross-platform system monitoring tool.

System Admin

Syntax

glances [OPTION]...

Common Options

Option	Description
`-s`	Server mode
`-c`	Client mode
`-w`	Web interface
`-t`	Interval

Examples

Launch glances

$ glances

Web interface

$ glances -w

pidof

Find PID of running program.

General

Syntax

pidof [OPTION]... PROGRAM...

Common Options

Option	Description
`-s`	Single PID
`-x`	Include scripts
`-o`	Omit PIDs

Examples

Find PID

$ pidof firefox

pmap

Report memory map of process.

System Admin

Syntax

pmap [OPTION]... PID

Common Options

Option	Description
`-x`	Extended format
`-d`	Device format
`-q`	Quiet mode

Examples

Show process memory

$ pmap 1234

strace

Trace system calls and signals.

System Admin

Syntax

strace [OPTION]... COMMAND

Common Options

Option	Description
`-p`	Attach to PID
`-e`	Filter system calls
`-f`	Follow child processes
`-o`	Output to file

Examples

Trace command execution

$ strace ls

Attach to running process

$ strace -p 1234

ltrace

Trace library function calls.

General

Syntax

ltrace [OPTION]... COMMAND

Common Options

Option	Description
`-p`	Attach to PID
`-e`	Filter functions
`-f`	Follow children
`-o`	Output to file

Examples

Trace library calls

$ ltrace ls

perf

Performance analysis tool for Linux.

General

Syntax

perf [SUBCOMMAND] [OPTION]...

Common Options

Option	Description
`stat`	Count events
`record`	Record events
`report`	Report events
`top`	Real-time profiling

Examples

Count CPU cycles

$ perf stat command

Profile command

$

perf record -g command
perf report

mpstat

Report CPU statistics per processor.

System Admin

Syntax

mpstat [OPTION]... [INTERVAL] [COUNT]

Common Options

Option	Description
`-P`	Specific CPU
`-A`	All information
`-u`	CPU usage

Examples

Show CPU stats

$ mpstat

Monitor every second

$ mpstat 1

iotop

Monitor I/O usage per process.

System Admin

Syntax

iotop [OPTION]...

Common Options

Option	Description
`-o`	Show only active processes
`-b`	Batch mode
`-d`	Delay
`-n`	Number of iterations

Examples

Monitor I/O in real-time

$ sudo iotop

iftop

Monitor network bandwidth usage.

Networking

Syntax

iftop [OPTION]...

Common Options

Option	Description
`-i`	Interface
`-n`	No DNS resolution
`-f`	Filter packets
`-p`	Promiscuous mode

Examples

Monitor network traffic

$ sudo iftop

Monitor specific interface

$ sudo iftop -i eth0

nload

Monitor network bandwidth with graphs.

Networking

Syntax

nload [OPTION]...

Common Options

Option	Description
`-u`	Unit (k/M/G)
`-U`	Update interval
`-t`	Graph refresh time

Examples

Monitor traffic

$ nload

ip

Show/manipulate network interfaces.

Networking

Syntax

ip [OPTION]... OBJECT {COMMAND}

Common Options

Option	Description
`link`	Network interface
`addr`	IP addresses
`route`	Routing table
`neigh`	ARP table

Examples

Show interfaces

$ ip link show

Show IP addresses

$ ip addr show

ifconfig

Configure network interfaces (deprecated).

Networking

Syntax

ifconfig [OPTION]... [INTERFACE]

Common Options

Option	Description
`up`	Activate interface
`down`	Deactivate
`add`	Add address
`del`	Remove address

Examples

Show interfaces

$ ifconfig

Configure interface

$ ifconfig eth0 192.168.1.10

iwconfig

Configure wireless network interface.

Networking

Syntax

iwconfig [OPTION]... [INTERFACE]

Common Options

Option	Description
`essid`	Network name
`mode`	Operation mode
`key`	Encryption key
`freq`	Channel frequency

Examples

Show wireless settings

$ iwconfig

Connect to network

$ iwconfig wlan0 essid "MyNetwork"

iw

Modern wireless device configuration tool.

General

Syntax

iw [OPTION]... COMMAND

Common Options

Option	Description
`dev`	Device operations
`phy`	Physical device
`info`	Show info
`scan`	Scan networks

Examples

List wireless devices

$ iw dev

Scan for networks

$ iw dev wlan0 scan

ss

Show socket statistics.

General

Syntax

ss [OPTION]...

Common Options

Option	Description
`-t`	TCP sockets
`-u`	UDP sockets
`-l`	Listening sockets
`-n`	Numeric output
`-p`	Process info

Examples

Show all TCP connections

$ ss -t

Show listening ports

$ ss -l

netstat

Display network connections and statistics.

Networking

Syntax

netstat [OPTION]...

Common Options

Option	Description
`-t`	TCP
`-u`	UDP
`-l`	Listening
`-p`	Process info
`-r`	Routing table

Examples

Show all connections

$ netstat -tulpn

Show routing table

$ netstat -r

route

Display/modify routing table.

General

Syntax

route [OPTION]...

Common Options

Option	Description
`-n`	Numeric output
`add`	Add route
`del`	Delete route
`-A`	Address family

Examples

Show routing table

$ route -n

Add default gateway

$ route add default gw 192.168.1.1

arp

Display/modify ARP cache.

General

Syntax

arp [OPTION]...

Common Options

Option	Description
`-n`	Numeric output
`-a`	Show all entries
`-d`	Delete entry
`-s`	Add entry

Examples

Show ARP table

$ arp -n

ping

Test network connectivity.

Networking

Syntax

ping [OPTION]... HOST

Common Options

Option	Description
`-c`	Count
`-i`	Interval
`-s`	Packet size
`-4/-6`	IPv4/IPv6
`-W`	Timeout

Examples

Test connectivity

$ ping google.com

Ping with count

$ ping -c 5 8.8.8.8

ping6

Test IPv6 network connectivity.

Networking

Syntax

ping6 [OPTION]... HOST

Examples

Test IPv6 connectivity

$ ping6 ipv6.google.com

traceroute

Trace path to network host.

Networking

Syntax

traceroute [OPTION]... HOST

Common Options

Option	Description
`-n`	No DNS
`-w`	Wait time
`-m`	Max hops
`-I`	ICMP packets

Examples

Trace route

$ traceroute google.com

No DNS resolution

$ traceroute -n 8.8.8.8

tracepath

Trace network path with MTU discovery.

Networking

Syntax

tracepath [OPTION]... HOST

Common Options

Option	Description
`-n`	Numeric output
`-l`	Initial packet length

Examples

Trace path

$ tracepath google.com

mtr

Combined traceroute and ping tool.

Networking

Syntax

mtr [OPTION]... HOST

Common Options

Option	Description
`-r`	Report mode
`-c`	Number of pings
`-n`	No DNS
`-i`	Interval

Examples

Run mtr

$ mtr google.com

Generate report

$ mtr -r -c 10 google.com

dig

DNS lookup utility.

General

Syntax

dig [OPTION]... DOMAIN [TYPE]

Common Options

Option	Description
`+short`	Short output
`+trace`	Trace delegation
`@server`	Specific server
`-x`	Reverse lookup

Examples

Lookup A record

$ dig google.com

Short output

$ dig +short google.com

Reverse lookup

$ dig -x 8.8.8.8

host

Simple DNS lookup tool.

General

Syntax

host [OPTION]... DOMAIN [SERVER]

Common Options

Option	Description
`-a`	All records
`-t`	Record type
`-v`	Verbose

Examples

Lookup domain

$ host google.com

Specific record type

$ host -t MX google.com

nslookup

Query DNS nameservers.

General

Syntax

nslookup [OPTION]... [HOST]

Common Options

Option	Description
`-type=`	Record type
`-timeout=`	Timeout
`-debug`	Debug mode

Examples

Lookup domain

$ nslookup google.com

Interactive mode

$ nslookup

curl

Transfer data from/to servers.

General

Syntax

curl [OPTION]... URL

Common Options

Option	Description
`-o`	Output to file
`-L`	Follow redirects
`-v`	Verbose
`-H`	Header
`-d`	Data
`-X`	Method

Examples

Download file

$ curl -O https://example.com/file.txt

Send POST request

$ curl -d "key=value" https://example.com/api

wget

Retrieve files from web.

File Management

Syntax

wget [OPTION]... URL

Common Options

Option	Description
`-O`	Output file
`-c`	Resume download
`-r`	Recursive
`-q`	Quiet mode
`-P`	Directory prefix

Examples

Download file

$ wget https://example.com/file.zip

Resume download

$ wget -c https://example.com/file.zip

aria2c

High-performance download utility.

General

Syntax

aria2c [OPTION]... URL

Common Options

Option	Description
`-x`	Connection count
`-o`	Output file
`-s`	Split count
`-d`	Directory

Examples

Download file

$ aria2c https://example.com/file.zip

Download with multiple connections

$ aria2c -x 16 https://example.com/file.zip

ftp

Classic file transfer protocol client.

File Management

Syntax

ftp [OPTION]... [HOST]

Common Options

Option	Description
`-i`	Turn off interactive
`-n`	No auto-login
`-v`	Verbose

Examples

Connect to FTP

$ ftp example.com

sftp

SSH File Transfer Protocol client.

File Management

Syntax

sftp [OPTION]... [USER@]HOST

Common Options

Option	Description
`-b`	Batch file
`-P`	Port
`-v`	Verbose

Examples

Connect via SFTP

$ sftp [email protected]

scp

Copy files over SSH.

File Management

Syntax

scp [OPTION]... SOURCE TARGET

Common Options

Option	Description
`-r`	Recursive
`-P`	Port
`-i`	Identity file
`-C`	Compression

Examples

Copy file to remote

$ scp file.txt user@host:/path/

Copy remote to local

$ scp user@host:/path/file.txt .

rsync

Efficient file synchronization.

File Management

Syntax

rsync [OPTION]... SOURCE DEST

Common Options

Option	Description
`-a`	Archive mode
`-z`	Compression
`-v`	Verbose
`--delete`	Delete extra files
`-P`	Progress
`-e`	Remote shell

Examples

Sync local directory

$ rsync -av /source/ /dest/

Sync over SSH

$ rsync -avz -e ssh /local user@host:/remote/

ssh

Secure shell client for remote access.

User Management

Syntax

ssh [OPTION]... [USER@]HOST [COMMAND]

Common Options

Option	Description
`-p`	Port
`-i`	Identity file
`-v`	Verbose
`-X`	X11 forwarding
`-L`	Local forwarding

Examples

Connect to remote

$ ssh user@hostname

Run remote command

$ ssh user@hostname "ls -la"

ssh-keygen

Generate SSH key pairs.

General

Syntax

ssh-keygen [OPTION]...

Common Options

Option	Description
`-t`	Key type (rsa, ed25519)
`-b`	Bits
`-f`	Output file
`-C`	Comment
`-p`	Change passphrase

Examples

Generate SSH key

$ ssh-keygen -t ed25519 -C "[email protected]"

ssh-copy-id

Install public key to remote server.

General

Syntax

ssh-copy-id [OPTION]... [USER@]HOST

Common Options

Option	Description
`-i`	Identity file
`-p`	Port
`-f`	Force

Examples

Copy key to remote

$ ssh-copy-id user@hostname

ssh-agent

Manage SSH private keys.

General

Syntax

ssh-agent [OPTION]... [COMMAND]

Common Options

Option	Description
`-s`	Bourne shell output
`-c`	C shell output
`-k`	Kill agent
`-t`	Timeout

Examples

Start agent

$ eval $(ssh-agent)

ssh-add

Add private key to ssh-agent.

General

Syntax

ssh-add [OPTION]... [FILE]

Common Options

Option	Description
`-l`	List keys
`-d`	Delete key
`-D`	Delete all
`-t`	Timeout

Examples

Add default key

$ ssh-add

List loaded keys

$ ssh-add -l

telnet

Unencrypted remote terminal client.

General

Syntax

telnet [OPTION]... HOST [PORT]

Common Options

Option	Description
`-a`	Auto login
`-l`	User

Examples

Connect via telnet

$ telnet hostname

nc

Network tool for reading/writing connections.

Networking

Syntax

nc [OPTION]... [HOST] [PORT]

Common Options

Option	Description
`-l`	Listen mode
`-p`	Local port
`-v`	Verbose
`-u`	UDP
`-z`	Zero I/O mode

Examples

Connect to server

$ nc example.com 80

Listen on port

$ nc -l 1234

ncat

Enhanced netcat implementation.

General

Syntax

ncat [OPTION]... [HOST] [PORT]

Common Options

Option	Description
`-l`	Listen
`-k`	Keep listening
`-s`	Source address
`--ssl`	SSL encryption

Examples

Listen on port

$ ncat -l 1234

SSL listener

$ ncat --ssl -l 1234

socat

Multipurpose socket relay tool.

Networking

Syntax

socat [OPTION]... ADDRESS ADDRESS

Common Options

Option	Description
`-v`	Verbose
`-x`	Hex dump
`-d`	Debug
`-T`	Timeout

Examples

Forward port

$ socat TCP-LISTEN:8080 TCP:localhost:80

tcpdump

Capture and analyze network packets.

Networking

Syntax

tcpdump [OPTION]... [EXPRESSION]

Common Options

Option	Description
`-i`	Interface
`-n`	Numeric output
`-w`	Write to file
`-r`	Read from file
`-c`	Count
`-v`	Verbose

Examples

Capture packets

$ sudo tcpdump -i eth0

Save to file

$ sudo tcpdump -i eth0 -w capture.pcap

tshark

Wireshark command-line packet analyzer.

General

Syntax

tshark [OPTION]...

Common Options

Option	Description
`-i`	Interface
`-r`	Read file
`-Y`	Display filter
`-w`	Write file

Examples

Capture packets

$ sudo tshark -i eth0

wireshark

Graphical network packet analyzer.

Networking

Syntax

wireshark [OPTION]...

Common Options

Option	Description
`-i`	Interface
`-r`	Read file
`-k`	Start capture

Examples

Start Wireshark

$ wireshark

nmap

Network discovery and security scanning.

Networking

Syntax

nmap [OPTION]... [HOST]

Common Options

Option	Description
`-sS`	SYN scan
`-sU`	UDP scan
`-p`	Port range
`-O`	OS detection
`-A`	Aggressive scan

Examples

Scan host

$ nmap 192.168.1.1

Scan with OS detection

$ sudo nmap -O 192.168.1.1

arp-scan

Discover hosts via ARP.

Networking

Syntax

arp-scan [OPTION]... [INTERFACE]

Common Options

Option	Description
`-l`	Local network
`-r`	Retries
`-t`	Timeout

Examples

Scan local network

$ sudo arp-scan -l

ethtool

Display/manage ethernet device settings.

General

Syntax

ethtool [OPTION]... DEVICE

Common Options

Option	Description
`-s`	Set settings
`-k`	Offload settings
`-p`	Blink LED
`-g`	Ring buffer

Examples

Show interface info

$ ethtool eth0

Show link status

$ ethtool eth0 | grep Link

nmcli

NetworkManager command-line interface.

Networking

Syntax

nmcli [OPTION]... OBJECT {COMMAND}

Common Options

Option	Description
`dev`	Device operations
`con`	Connection operations
`radio`	Radio operations
`general`	General settings

Examples

Show connections

$ nmcli con show

Connect to Wi-Fi

$ nmcli dev wifi connect "SSID" password "pass"

nmtui

NetworkManager text UI.

Networking

Syntax

nmtui [OPTION]...

Common Options

Option	Description
`edit`	Edit connection
`connect`	Connect to network
`hostname`	Set hostname

Examples

Launch NetworkManager TUI

$ nmtui

resolvectl

Control systemd-resolved DNS settings.

System Admin

Syntax

resolvectl [OPTION]... [COMMAND]

Common Options

Option	Description
`status`	Show status
`set-dns`	Set DNS servers
`query`	Query DNS

Examples

Show DNS status

$ resolvectl status

Set DNS server

$ resolvectl set-dns eth0 8.8.8.8

iptables

Configure IPv4 firewall rules.

Networking

Syntax

iptables [OPTION]... [COMMAND] [CHAIN] [RULE]

Common Options

Option	Description
`-A`	Append rule
`-D`	Delete rule
`-L`	List rules
`-F`	Flush rules
`-P`	Policy

Examples

List rules

$ sudo iptables -L

Allow port 80

$ sudo iptables -A INPUT -p tcp --dport 80 -j ACCEPT

nft

Nftables firewall tool (iptables replacement).

Networking

Syntax

nft [OPTION]... {COMMAND}

Common Options

Option	Description
`list`	List rules
`add`	Add rule
`delete`	Delete rule
`flush`	Flush rules

Examples

List all rules

$ sudo nft list ruleset

Add rule

$ sudo nft add rule inet filter input tcp dport 80 accept

ufw

Simplified firewall management.

General

Syntax

ufw [OPTION]... [COMMAND]

Common Options

Option	Description
`enable`	Enable firewall
`disable`	Disable firewall
`allow`	Allow port/service
`deny`	Deny port/service
`status`	Show status

Examples

Enable firewall

$ sudo ufw enable

Allow SSH

$ sudo ufw allow ssh

firewall-cmd

FirewallD command-line interface.

General

Syntax

firewall-cmd [OPTION]... [COMMAND]

Common Options

Option	Description
`--state`	Show state
`--zone`	Zone
`--add-port`	Add port
`--reload`	Reload rules
`--list-all`	List all

Examples

Add service

$ sudo firewall-cmd --add-service=http

List all rules

$ sudo firewall-cmd --list-all

fail2ban-client

Fail2ban client for security monitoring.

General

Syntax

fail2ban-client [OPTION]... [COMMAND]

Common Options

Option	Description
`status`	Show status
`reload`	Reload configuration
`ping`	Test connection

Examples

Check status

$ sudo fail2ban-client status

docker

Docker container engine management.

General

Syntax

docker [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`ps`	List containers
`run`	Run container
`stop`	Stop container
`rm`	Remove container
`images`	List images

Examples

Run container

$ docker run hello-world

List containers

$ docker ps -a

docker-compose

Define and run multi-container Docker apps.

General

Syntax

docker-compose [OPTION]... [COMMAND]...

Common Options

Option	Description
`up`	Start containers
`down`	Stop containers
`logs`	View logs
`exec`	Execute command
`build`	Build services

Examples

Start services

$ docker-compose up -d

Stop services

$ docker-compose down

podman

Container management tool (daemonless).

General

Syntax

podman [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`ps`	List containers
`run`	Run container
`pull`	Pull image
`push`	Push image
`logs`	View logs

Examples

Run container

$ podman run hello-world

List containers

$ podman ps -a

buildah

Build container images.

General

Syntax

buildah [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`bud`	Build image
`from`	Create working container
`commit`	Save container
`push`	Push image

Examples

Build image

$ buildah bud -t myimage .

skopeo

Manage container images.

General

Syntax

skopeo [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`inspect`	Inspect image
`copy`	Copy image
`sync`	Sync images
`list-tags`	List tags

Examples

Inspect image

$ skopeo inspect docker://docker.io/library/nginx

nerdctl

Docker-compatible containerd CLI.

General

Syntax

nerdctl [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`ps`	List containers
`run`	Run container
`images`	List images
`pull`	Pull image

Examples

Run container

$ nerdctl run hello-world

kubectl

Kubernetes command-line tool.

General

Syntax

kubectl [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`get`	Get resources
`describe`	Describe resources
`apply`	Apply configuration
`logs`	View logs
`exec`	Execute command

Examples

Get pods

$ kubectl get pods

Apply configuration

$ kubectl apply -f deployment.yaml

minikube

Run Kubernetes locally.

General

Syntax

minikube [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`start`	Start cluster
`stop`	Stop cluster
`delete`	Delete cluster
`status`	Show status
`dashboard`	Open dashboard

Examples

Start cluster

$ minikube start

Open dashboard

$ minikube dashboard

kind

Run Kubernetes clusters in Docker containers.

General

Syntax

kind [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`create`	Create cluster
`delete`	Delete cluster
`load`	Load images
`export`	Export logs

Examples

Create cluster

$ kind create cluster

helm

Kubernetes package manager (Helm).

General

Syntax

helm [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`install`	Install chart
`list`	List releases
`upgrade`	Upgrade release
`uninstall`	Uninstall release

Examples

Install chart

$ helm install nginx bitnami/nginx

List releases

$ helm list

crictl

Container runtime CLI for Kubernetes.

General

Syntax

crictl [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`ps`	List containers
`images`	List images
`pods`	List pods
`logs`	View logs

Examples

List containers

$ crictl ps

systemctl

Control systemd services.

System Admin

Syntax

systemctl [OPTION]... COMMAND [NAME]...

Common Options

Option	Description
`start`	Start service
`stop`	Stop service
`restart`	Restart service
`status`	Show status
`enable`	Enable service
`disable`	Disable service

Examples

Start service

$ sudo systemctl start nginx

Check status

$ systemctl status nginx

service

Run System V init scripts.

Networking

Syntax

service [OPTION]... SCRIPT [COMMAND]

Common Options

Option	Description
`--status-all`	Show all services
`start`	Start service
`stop`	Stop service
`restart`	Restart service

Examples

Start service

$ sudo service nginx start

loginctl

Control systemd login sessions.

System Admin

Syntax

loginctl [OPTION]... [COMMAND]

Common Options

Option	Description
`list-sessions`	List sessions
`list-users`	List users
`show-user`	Show user info
`lock-session`	Lock session

Examples

List sessions

$ loginctl list-sessions

busctl

Introspect D-Bus bus.

General

Syntax

busctl [OPTION]... [COMMAND]

Common Options

Option	Description
`list`	List services
`introspect`	Introspect service
`call`	Call method
`monitor`	Monitor messages

Examples

List services

$ busctl list

systemd-analyze

Analyze systemd boot performance.

System Admin

Syntax

systemd-analyze [OPTION]... [COMMAND]

Common Options

Option	Description
`time`	Boot time
`blame`	Service start times
`critical-chain`	Critical path
`plot`	Plot graph

Examples

Show boot time

$ systemd-analyze time

Find slow services

$ systemd-analyze blame

machinectl

Control systemd containers.

System Admin

Syntax

machinectl [OPTION]... [COMMAND]

Common Options

Option	Description
`list`	List containers
`status`	Show status
`login`	Login to container
`shell`	Run shell

Examples

List containers

$ machinectl list

localectl

Control system locale/keymap settings.

System Admin

Syntax

localectl [OPTION]... [COMMAND]

Common Options

Option	Description
`status`	Show current settings
`set-locale`	Set locale
`set-keymap`	Set keymap
`list-locales`	List locales

Examples

Show settings

$ localectl status

Set locale

$ sudo localectl set-locale LANG=en_US.UTF-8

bootctl

Control systemd-boot boot manager.

System Admin

Syntax

bootctl [OPTION]... [COMMAND]

Common Options

Option	Description
`status`	Show status
`install`	Install boot loader
`update`	Update entries
`list`	List entries

Examples

Show boot status

$ bootctl status

systemd-run

Run commands as transient systemd units.

System Admin

Syntax

systemd-run [OPTION]... COMMAND

Common Options

Option	Description
`--unit`	Unit name
`--description`	Description
`--user`	User scope

Examples

Run command

$ systemd-run --unit=mytask command

apt

APT package management (modern).

General

Syntax

apt [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`update`	Update package lists
`upgrade`	Upgrade packages
`install`	Install package
`remove`	Remove package
`search`	Search packages

Examples

Update packages

$ sudo apt update

Install package

$ sudo apt install nginx

apt-get

Legacy APT package management.

General

Syntax

apt-get [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`install`	Install package
`remove`	Remove package
`update`	Update lists
`upgrade`	Upgrade packages

Examples

Update packages

$ sudo apt-get update

apt-cache

APT package query tool.

General

Syntax

apt-cache [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`show`	Show package info
`search`	Search packages
`depends`	Show dependencies
`stats`	Show statistics

Examples

Search for package

$ apt-cache search nginx

Show package info

$ apt-cache show nginx

dpkg

Debian package management tool.

General

Syntax

dpkg [OPTION]... [COMMAND]

Common Options

Option	Description
`-i`	Install package
`-r`	Remove package
`-l`	List packages
`-s`	Show status

Examples

Install .deb

$ sudo dpkg -i package.deb

List installed

$ dpkg -l

dpkg-query

Query dpkg package database.

General

Syntax

dpkg-query [OPTION]... [COMMAND]

Common Options

Option	Description
`-l`	List packages
`-s`	Show package status
`-f`	Format output

Examples

List packages

$ dpkg-query -l

aptitude

Advanced package management frontend.

General

Syntax

aptitude [OPTION]... [COMMAND]

Common Options

Option	Description
`search`	Search packages
`install`	Install package
`remove`	Remove package
`update`	Update lists

Examples

Search package

$ aptitude search nginx

snap

Snap package management.

General

Syntax

snap [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`install`	Install snap
`remove`	Remove snap
`list`	List snaps
`find`	Find snaps
`refresh`	Update snaps

Examples

Install snap

$ sudo snap install hello-world

List snaps

$ snap list

flatpak

Flatpak application management.

General

Syntax

flatpak [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`install`	Install app
`uninstall`	Remove app
`list`	List apps
`run`	Run app

Examples

Install app

$ flatpak install flathub org.videolan.VLC

Run app

$ flatpak run org.videolan.VLC

rpm

RPM package management.

General

Syntax

rpm [OPTION]... [COMMAND]

Common Options

Option	Description
`-i`	Install package
`-U`	Upgrade package
`-e`	Erase package
`-q`	Query package
`-V`	Verify package

Examples

Install RPM

$ sudo rpm -i package.rpm

List installed

$ rpm -qa

yum

Yellowdog Updater Modified (legacy).

General

Syntax

yum [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`install`	Install package
`remove`	Remove package
`update`	Update packages
`search`	Search packages

Examples

Install package

$ sudo yum install nginx

dnf

Modern RPM package manager (replaces yum).

General

Syntax

dnf [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`install`	Install package
`remove`	Remove package
`update`	Update packages
`search`	Search packages
`info`	Show info

Examples

Install package

$ sudo dnf install nginx

Search package

$ dnf search nginx

zypper

SUSE package management.

General

Syntax

zypper [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`install`	Install package
`remove`	Remove package
`update`	Update packages
`search`	Search packages

Examples

Install package

$ sudo zypper install nginx

pacman

Arch Linux package manager.

General

Syntax

pacman [OPTION]... [COMMAND]

Common Options

Option	Description
`-S`	Install package
`-R`	Remove package
`-Q`	Query packages
`-Sy`	Sync databases

Examples

Install package

$ sudo pacman -S nginx

Update system

$ sudo pacman -Syu

yay

Arch AUR package helper.

General

Syntax

yay [OPTION]... [COMMAND]

Common Options

Option	Description
`-S`	Install package
`-R`	Remove package
`-Q`	Query packages
`-Y`	Yay commands

Examples

Install from AUR

$ yay -S package-name

paru

Arch AUR package helper (Rust-based).

General

Syntax

paru [OPTION]... [COMMAND]

Common Options

Option	Description
`-S`	Install package
`-R`	Remove package
`-Q`	Query packages
`-G`	Get PKGBUILD

Examples

Install from AUR

$ paru -S package-name

emerge

Gentoo package manager.

General

Syntax

emerge [OPTION]... [COMMAND] [PACKAGE]

Common Options

Option	Description
`-p`	Pretend
`-v`	Verbose
`-u`	Update
`-D`	Deep dependencies

Examples

Install package

$ sudo emerge -v nginx

Update system

$ sudo emerge -uD world

xbps-install

Void Linux package installer.

General

Syntax

xbps-install [OPTION]... [PACKAGE]...

Common Options

Option	Description
`-S`	Sync repository
`-u`	Update packages
`-r`	Root directory

Examples

Install package

$ sudo xbps-install -S nginx

apk

Alpine Linux package manager.

General

Syntax

apk [OPTION]... COMMAND [PACKAGE]...

Common Options

Option	Description
`add`	Install package
`del`	Remove package
`update`	Update repositories
`upgrade`	Upgrade packages

Examples

Install package

$ apk add nginx

nix-env

Nix package management.

General

Syntax

nix-env [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`-i`	Install package
`-e`	Erase package
`-q`	Query packages
`-u`	Upgrade packages

Examples

Install package

$ nix-env -iA nixpkgs.hello

guix

GNU Guix package manager.

General

Syntax

guix [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`package`	Package operations
`build`	Build package
`pull`	Update guix

Examples

Install package

$ guix package -i hello

tar

Tape archive utility.

Archiving

Syntax

tar [OPTION]... [ARCHIVE] [FILE]...

Common Options

Option	Description
`-c`	Create archive
`-x`	Extract archive
`-f`	Archive file
`-v`	Verbose
`-z`	gzip compression
`-j`	bzip2 compression

Examples

Create tar

$ tar -cvf archive.tar files/

Extract tar

$ tar -xvf archive.tar

With gzip

$ tar -czvf archive.tar.gz files/

gzip

Compress files with gzip.

File Management

Syntax

gzip [OPTION]... [FILE]...

Common Options

Option	Description
`-d`	Decompress
`-k`	Keep original
`-v`	Verbose
`-r`	Recursive

Examples

Compress file

$ gzip file.txt

Decompress

$ gunzip file.txt.gz

gunzip

Decompress gzip files.

File Management

Syntax

gunzip [OPTION]... [FILE]...

Common Options

Option	Description
`-c`	Output to stdout
`-k`	Keep compressed file
`-f`	Force

Examples

Decompress file

$ gunzip file.txt.gz

bzip2

Compress files with bzip2.

File Management

Syntax

bzip2 [OPTION]... [FILE]...

Common Options

Option	Description
`-d`	Decompress
`-k`	Keep original
`-v`	Verbose
`-z`	Compress

Examples

Compress file

$ bzip2 file.txt

bunzip2

Decompress bzip2 files.

File Management

Syntax

bunzip2 [OPTION]... [FILE]...

Common Options

Option	Description
`-k`	Keep compressed file
`-f`	Force
`-v`	Verbose

Examples

Decompress

$ bunzip2 file.txt.bz2

xz

Compress files with LZMA.

File Management

Syntax

xz [OPTION]... [FILE]...

Common Options

Option	Description
`-d`	Decompress
`-k`	Keep original
`-v`	Verbose
`-z`	Compress

Examples

Compress

$ xz file.txt

unxz

Decompress xz files.

File Management

Syntax

unxz [OPTION]... [FILE]...

Common Options

Option	Description
`-k`	Keep compressed
`-f`	Force

Examples

Decompress

$ unxz file.txt.xz

zip

Create zip archives.

Networking

Syntax

zip [OPTION]... [ARCHIVE] [FILE]...

Common Options

Option	Description
`-r`	Recursive
`-d`	Delete from archive
`-u`	Update
`-q`	Quiet

Examples

Create zip

$ zip archive.zip files/

unzip

Extract zip archives.

Networking

Syntax

unzip [OPTION]... [ARCHIVE]

Common Options

Option	Description
`-d`	Extract to directory
`-l`	List contents
`-n`	Never overwrite
`-o`	Overwrite

Examples

Extract zip

$ unzip archive.zip

Extract to directory

$ unzip archive.zip -d /target/

7z

7-Zip file archiver.

File Management

Syntax

7z [OPTION]... COMMAND [ARCHIVE] [FILE]...

Common Options

Option	Description
`a`	Add to archive
`x`	Extract
`t`	Test archive
`l`	List contents

Examples

Create 7z archive

$ 7z a archive.7z files/

Extract

$ 7z x archive.7z

unrar

Extract RAR archives.

Archiving

Syntax

unrar [OPTION]... COMMAND [ARCHIVE]

Common Options

Option	Description
`x`	Extract full path
`e`	Extract without paths
`l`	List contents

Examples

Extract RAR

$ unrar x archive.rar

rar

Create/extract RAR archives (proprietary).

Archiving

Syntax

rar [OPTION]... COMMAND [ARCHIVE] [FILE]...

Common Options

Option	Description
`a`	Add to archive
`x`	Extract
`t`	Test archive

Examples

Create RAR

$ rar a archive.rar files/

cpio

Copy files to/from archive.

File Management

Syntax

cpio [OPTION]... [MODE]

Common Options

Option	Description
`-i`	Extract
`-o`	Create
`-p`	Copy pass-through
`-v`	Verbose

Examples

Create cpio archive

$ find . | cpio -ov > archive.cpio

Extract

$ cpio -iv < archive.cpio

ar

Create and manipulate archive files.

File Management

Syntax

ar [OPTION]... [ARCHIVE] [FILE]...

Common Options

Option	Description
`r`	Replace files
`x`	Extract files
`t`	List contents
`d`	Delete files

Examples

Create archive

$ ar r archive.a file1.o file2.o

zstd

Zstandard compression tool.

Archiving

Syntax

zstd [OPTION]... [FILE]...

Common Options

Option	Description
`-d`	Decompress
`-k`	Keep original
`-o`	Output file
`-v`	Verbose

Examples

Compress file

$ zstd file.txt

Decompress

$ zstd -d file.txt.zst

lz4

LZ4 compression tool.

Archiving

Syntax

lz4 [OPTION]... [FILE]...

Common Options

Option	Description
`-d`	Decompress
`-z`	Compress
`-k`	Keep original

Examples

Compress

$ lz4 file.txt

openssl

OpenSSL cryptography toolkit.

General

Syntax

openssl [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`enc`	Encryption
`x509`	Certificate
`genrsa`	Generate RSA key
`req`	Certificate request
`s_client`	SSL client

Examples

Generate private key

$ openssl genrsa -out key.pem 2048

Encrypt file

$ openssl enc -aes-256-cbc -in file.txt -out file.enc

gpg

Encryption and signing tool.

General

Syntax

gpg [OPTION]... [COMMAND]

Common Options

Option	Description
`--gen-key`	Generate key
`--encrypt`	Encrypt
`--decrypt`	Decrypt
`--sign`	Sign
`--verify`	Verify

Examples

Encrypt file

$ gpg -c file.txt

Decrypt

$ gpg file.txt.gpg

sha256sum

Calculate SHA-256 hash.

General

Syntax

sha256sum [OPTION]... [FILE]...

Common Options

Option	Description
`-c`	Check checksums
`-b`	Binary mode

Examples

Calculate hash

$ sha256sum file.txt

sha1sum

Calculate SHA-1 hash.

General

Syntax

sha1sum [OPTION]... [FILE]...

Common Options

Option	Description
`-c`	Check checksums

Examples

Calculate hash

$ sha1sum file.txt

md5sum

Calculate MD5 hash.

General

Syntax

md5sum [OPTION]... [FILE]...

Common Options

Option	Description
`-c`	Check checksums

Examples

Calculate MD5

$ md5sum file.txt

cksum

Calculate CRC checksum.

General

Syntax

cksum [OPTION]... [FILE]...

Common Options

Option	Description
`-a`	Algorithm

Examples

Calculate checksum

$ cksum file.txt

base64

Base64 encode/decode data.

General

Syntax

base64 [OPTION]... [FILE]

Common Options

Option	Description
`-d`	Decode
`-w`	Wrap width
`-i`	Ignore non-alphabet chars

Examples

Encode file

$ base64 file.txt

Decode

$ base64 -d encoded.txt

shred

Overwrite files to prevent recovery.

File Management

Syntax

shred [OPTION]... [FILE]...

Common Options

Option	Description
`-f`	Force
`-n`	Number of passes
`-v`	Verbose
`-z`	Add zero pass

Examples

Secure delete

$ shred -vfz file.txt

chattr

Change file attributes on ext2/3/4.

File Management

Syntax

chattr [OPTION]... [FILE]...

Common Options

Option	Description
`+i`	Immutable
`-i`	Remove immutable
`+a`	Append only
`-R`	Recursive

Examples

Make immutable

$ sudo chattr +i file.txt

lsattr

List file attributes.

File Management

Syntax

lsattr [OPTION]... [FILE]...

Common Options

Option	Description
`-R`	Recursive
`-a`	Include hidden
`-d`	Directories

Examples

List attributes

$ lsattr file.txt

cryptsetup

Manage LUKS encrypted volumes.

General

Syntax

cryptsetup [OPTION]... COMMAND [DEVICE]

Common Options

Option	Description
`luksFormat`	Create LUKS partition
`luksOpen`	Open LUKS
`luksClose`	Close LUKS
`luksAddKey`	Add passphrase

Examples

Create encrypted partition

$ sudo cryptsetup luksFormat /dev/sdb1

Open

$ sudo cryptsetup luksOpen /dev/sdb1 myencrypted

veracrypt

VeraCrypt volume management.

General

Syntax

veracrypt [OPTION]... [COMMAND]

Common Options

Option	Description
`-t`	Text mode
`-c`	Create volume
`-m`	Mount volume
`-d`	Dismount volume

Examples

Mount volume

$ veracrypt -t /path/to/volume.tc /mnt

dd

Convert and copy files/devices.

File Management

Syntax

dd [OPTION]...

Common Options

Option	Description
`if`	Input file
`of`	Output file
`bs`	Block size
`count`	Number of blocks
`status`	Progress display

Examples

Create disk image

$ dd if=/dev/sda of=disk.img bs=4M

Restore image

$ dd if=disk.img of=/dev/sda bs=4M

pv

Monitor data through pipeline.

Networking

Syntax

pv [OPTION]... [FILE]...

Common Options

Option	Description
`-s`	Size
`-L`	Rate limit
`-c`	Cursor movement
`-p`	Progress bar

Examples

Copy with progress

$ pv file.txt > destination

od

Display file in octal/hex format.

File Management

Syntax

od [OPTION]... [FILE]...

Common Options

Option	Description
`-t`	Output type
`-A`	Address base
`-x`	Hex
`-c`	ASCII chars

Examples

Display in hex

$ od -x file.bin

hexdump

Display file in hexadecimal.

File Management

Syntax

hexdump [OPTION]... [FILE]...

Common Options

Option	Description
`-C`	Canonical hex+ASCII
`-n`	Length
`-v`	Verbose

Examples

Hex dump

$ hexdump -C file.bin

xxd

Create hex dump or reverse.

General

Syntax

xxd [OPTION]... [FILE]

Common Options

Option	Description
`-r`	Reverse (hex to binary)
`-p`	Plain hex
`-i`	C include style

Examples

Hex dump

$ xxd file.bin

Reverse hex

$ xxd -r hex.txt > file.bin

hd

hexdump -C alias (hex+ASCII display).

screen [OPTION]... [COMMAND]

Common Options

Option	Description
`-S`	Session name
`-r`	Resume session
`-ls`	List sessions
`-d`	Detach session

Examples

Start new session

$ screen -S mysession

Resume

$ screen -r mysession

List

$ screen -ls

tmux

Modern terminal multiplexer.

Networking

Syntax

tmux [OPTION]... [COMMAND]

Common Options

Option	Description
`new`	New session
`ls`	List sessions
`attach`	Attach session
`kill-session`	Kill session

Examples

New session

$ tmux new -s mysession

List sessions

$ tmux ls

Attach

$ tmux attach -t mysession

byobu

Enhanced tmux/screen wrapper.

General

Syntax

byobu [OPTION]... [COMMAND]

Examples

Start byobu

$ byobu

bash

GNU Bourne-Again SHell.

User Management

Syntax

bash [OPTION]... [FILE]

Common Options

Option	Description
`-c`	Execute command
`-i`	Interactive mode
`-x`	Debug mode
`-v`	Verbose mode

Examples

Run script

$ bash script.sh

Execute command

$ bash -c "echo Hello"

sh

Bourne shell (typically dash or bash).

User Management

Syntax

sh [OPTION]... [FILE]

Common Options

Option	Description
`-c`	Execute command
`-n`	Syntax check

Examples

Run script

$ sh script.sh

zsh

Z shell (enhanced bash alternative).

User Management

Syntax

zsh [OPTION]... [FILE]

Common Options

Option	Description
`-c`	Execute command
`-i`	Interactive

Examples

Start zsh

$ zsh

fish

Friendly interactive shell.

User Management

Syntax

fish [OPTION]... [FILE]

Common Options

Option	Description
`-c`	Execute command
`-i`	Interactive

Examples

Start fish

$ fish

dash

POSIX-compliant shell.

User Management

Syntax

dash [OPTION]... [FILE]

Common Options

Option	Description
`-c`	Execute command

Examples

Run script

$ dash script.sh

ksh

Korn shell.

User Management

Syntax

ksh [OPTION]... [FILE]

Common Options

Option	Description
`-c`	Execute command

Examples

Start ksh

$ ksh

csh

C shell.

User Management

Syntax

csh [OPTION]... [FILE]

Common Options

Option	Description
`-c`	Execute command
`-f`	Fast startup

Examples

Start csh

$ csh

tcsh

Enhanced C shell.

User Management

Syntax

tcsh [OPTION]... [FILE]

Common Options

Option	Description
`-c`	Execute command
`-f`	Fast startup

Examples

Start tcsh

$ tcsh

ash

Almquist shell (BusyBox).

User Management

Syntax

ash [OPTION]... [FILE]

Common Options

Option	Description
`-c`	Execute command

Examples

Start ash

$ ash

envsubst

Substitute environment variables in text.

Text Processing

Syntax

envsubst [OPTION]... [SHELL-FORMAT]

Common Options

Option	Description
`-v`	Variables
`-V`	Show version

Examples

Substitute variables

$ echo 'Hello $USER' | envsubst

expr

Evaluate arithmetic and string expressions.

Text Processing

Syntax

expr [OPTION]... EXPRESSION

Common Options

Option	Description
`--help`	Help
`--version`	Version

Examples

Arithmetic

$ expr 2 + 2

String length

$ expr length "hello"

test

Evaluate conditional expressions.

General

Syntax

test [OPTION]... EXPRESSION

Common Options

Option	Description
`-f`	File exists
`-d`	Directory exists
`-z`	String empty
`-n`	String not empty

Examples

Test if file exists

$ test -f /etc/passwd && echo "Exists"

bc

Arbitrary precision calculator.

General

Syntax

bc [OPTION]... [FILE]

Common Options

Option	Description
`-l`	Math library
`-q`	Quiet mode
`-s`	POSIX mode

Examples

Calculate

$ echo "2+2" | bc

Math functions

$ echo "s(1)" | bc -l

dc

Reverse Polish notation calculator.

General

Syntax

dc [OPTION]... [FILE]

Common Options

Option	Description
`-e`	Execute expression
`-f`	Execute file

Examples

Calculate

$ echo "2 2 + p" | dc

factor

Factor numbers into primes.

General

Syntax

factor [OPTION]... NUMBER...

Examples

Factor number

$ factor 100

crontab

Manage cron jobs.

General

Syntax

crontab [OPTION]... [FILE]

Common Options

Option	Description
`-e`	Edit crontab
`-l`	List crontab
`-r`	Remove crontab
`-u`	User

Examples

Edit crontab

$ crontab -e

List jobs

$ crontab -l

at

Schedule one-time tasks.

General

Syntax

at [OPTION]... TIME

Common Options

Option	Description
`-f`	Read from file
`-l`	List jobs
`-d`	Delete jobs
`-m`	Send mail

Examples

Schedule command

$ echo "command" | at 14:00

List jobs

$ at -l

batch

Schedule when system load is low.

logger [OPTION]... [MESSAGE]

Common Options

Option	Description
`-t`	Tag
`-p`	Priority
`-i`	Include PID
`-s`	Also stdout

Examples

Log message

$ logger "System starting"

With tag

$ logger -t myscript "Done"

logrotate

Rotate, compress, and mail logs.

Archiving

Syntax

logrotate [OPTION]... CONFIGFILE

Common Options

Option	Description
`-f`	Force
`-v`	Verbose
`-s`	State file
`-d`	Debug

Examples

Run logrotate

$ sudo logrotate -v /etc/logrotate.conf

rsyslogd

System logging daemon.

System Admin

Syntax

rsyslogd [OPTION]...

Common Options

Option	Description
`-f`	Config file
`-d`	Debug
`-i`	PID file
`-n`	No fork

Examples

Start rsyslog

$ sudo rsyslogd

syslog-ng

syslog-ng logging daemon.

General

Syntax

syslog-ng [OPTION]...

Common Options

Option	Description
`-f`	Config file
`-d`	Debug
`-e`	Error messages
`-s`	Syntax check

Examples

Start syslog-ng

$ sudo syslog-ng

mail

Read and send mail.

General

Syntax

mail [OPTION]... [ADDRESS]

Common Options

Option	Description
`-s`	Subject
`-a`	Attach file
`-c`	CC

Examples

Send mail

$ echo "Body" | mail -s "Subject" [email protected]

mailx

Enhanced mail client.

General

Syntax

mailx [OPTION]... [ADDRESS]

Common Options

Option	Description
`-s`	Subject
`-a`	Attach
`-v`	Verbose

Examples

Send mail

$ echo "Body" | mailx -s "Subject" [email protected]

sendmail

Sendmail MTA (mail transport agent).

General

Syntax

sendmail [OPTION]... [ADDRESS]

Common Options

Option	Description
`-v`	Verbose
`-t`	Read recipients from message
`-f`	From address

Examples

Send mail

$ sendmail [email protected] < message.txt

mutt

Mutt email client.

General

Syntax

mutt [OPTION]... [ADDRESS]

Common Options

Option	Description
`-s`	Subject
`-a`	Attach file
`-f`	Mailbox file

Examples

Send mail

$ mutt -s "Subject" [email protected] < body.txt

alpine

Alpine email client.

General

Syntax

alpine [OPTION]...

Common Options

Option	Description
`-f`	Mailbox
`-h`	Help

Examples

Start alpine

$ alpine

wall

Send message to all logged in users.

User Management

Syntax

wall [OPTION]... [MESSAGE]

Examples

Send message

$ wall "System will reboot in 5 minutes"

write

Send message to specific user.

User Management

Syntax

write [USER] [TTY]

Examples

Send message

$

write username
Hello!

mesg

Control message reception.

General

Syntax

mesg [OPTION]... [COMMAND]

Common Options

Option	Description
`y`	Allow messages
`n`	Block messages
`v`	Verbose

Examples

Allow messages

$ mesg y

smbclient

SMB/CIFS file access client.

File Management

Syntax

smbclient [OPTION]... [SERVER]

Common Options

Option	Description
`-U`	User
`-L`	List shares
`-c`	Execute command

Examples

List shares

$ smbclient -L //server -U user

Connect

$ smbclient //server/share -U user

mount.cifs

Mount SMB/CIFS share.

Disk Usage

Syntax

mount.cifs [OPTION]... SOURCE TARGET

Common Options

Option	Description
`-o`	Options
`-U`	User
`-P`	Password

Examples

Mount share

$ sudo mount.cifs //server/share /mnt -o user=username

showmount

Show NFS exports.

General

Syntax

showmount [OPTION]... [HOST]

Common Options

Option	Description
`-e`	Show exports
`-d`	Directories
`-a`	All mounts

Examples

Show exports

$ showmount -e nfsserver

exportfs

Manage NFS exports.

General

Syntax

exportfs [OPTION]... [COMMAND]

Common Options

Option	Description
`-a`	Export all
`-r`	Re-export
`-u`	Unexport

Examples

Export shares

$ sudo exportfs -a

rpcinfo

Report RPC information.

General

Syntax

rpcinfo [OPTION]... [HOST]

Common Options

Option	Description
`-p`	Show ports
`-t`	TCP
`-u`	UDP

Examples

Show RPC services

$ rpcinfo -p

rpcbind

RPC port mapper.

General

Syntax

rpcbind [OPTION]...

Common Options

Option	Description
`-f`	Foreground
`-w`	WARM

Examples

Start rpcbind

$ sudo rpcbind

nfsstat

Display NFS statistics.

General

Syntax

nfsstat [OPTION]...

Common Options

Option	Description
`-c`	Client stats
`-s`	Server stats
`-l`	List mounts
`-n`	NFS stats

Examples

Show NFS stats

$ nfsstat

smbstatus

Show SMB connection status.

General

Syntax

smbstatus [OPTION]...

Common Options

Option	Description
`-L`	Locks
`-S`	Shares
`-u`	User

Examples

Show SMB status

$ smbstatus

smbpasswd

Change SMB password.

User Management

Syntax

smbpasswd [OPTION]... [USER]

Common Options

Option	Description
`-a`	Add user
`-x`	Delete user

Examples

Change password

$ smbpasswd username

useradd

Create new user account.

User Management

Syntax

useradd [OPTION]... USER

Common Options

Option	Description
`-m`	Create home directory
`-s`	Shell
`-G`	Groups
`-u`	UID
`-p`	Password

Examples

Add user

$ sudo useradd -m -s /bin/bash username

adduser

Interactive user creation (Debian/Ubuntu).

User Management

Syntax

adduser [OPTION]... USER

Common Options

Option	Description
`--home`	Home directory
`--shell`	Shell
`--group`	Group

Examples

Add user

$ sudo adduser username

usermod

Modify user account.

User Management

Syntax

usermod [OPTION]... USER

Common Options

Option	Description
`-s`	Shell
`-G`	Groups
`-l`	Login name
`-d`	Home directory

Examples

Change shell

$ sudo usermod -s /bin/zsh username

Add to group

$ sudo usermod -aG sudo username

userdel

Delete user account.

User Management

Syntax

userdel [OPTION]... USER

Common Options

Option	Description
`-r`	Remove home directory
`-f`	Force

Examples

Delete user

$ sudo userdel username

groupadd

Create new group.

User Management

Syntax

groupadd [OPTION]... GROUP

Common Options

Option	Description
`-g`	GID
`-r`	System group

Examples

Add group

$ sudo groupadd groupname

groupmod

Modify group.

User Management

Syntax

groupmod [OPTION]... GROUP

Common Options

Option	Description
`-n`	New name
`-g`	New GID

Examples

Rename group

$ sudo groupmod -n newname oldname

groupdel

Delete group.

User Management

Syntax

groupdel [OPTION]... GROUP

Examples

Delete group

$ sudo groupdel groupname

gpasswd

Administer group password.

User Management

Syntax

gpasswd [OPTION]... GROUP

Common Options

Option	Description
`-a`	Add user
`-d`	Delete user
`-A`	Admins
`-M`	Members

Examples

Add user to group

$ sudo gpasswd -a username groupname

newgrp

Change primary group.

chage [OPTION]... USER

Common Options

Option	Description
`-l`	List aging info
`-m`	Minimum days
`-M`	Maximum days
`-W`	Warning days
`-E`	Expire date

Examples

List password info

$ chage -l username

Set max days

$ sudo chage -M 90 username

faillog

Display login failure records.

User Management

Syntax

faillog [OPTION]...

Common Options

Option	Description
`-u`	User
`-m`	Max failures
`-r`	Reset
`-l`	Lock

Examples

Show failures

$ faillog

lastlog

Show last login times.

User Management

Syntax

lastlog [OPTION]...

Common Options

Option	Description
`-u`	User
`-t`	Time window
`-b`	Before time

Examples

Show all lastlog

$ lastlog

sudoedit

Edit files safely with elevated privileges.

File Management

Syntax

sudoedit [OPTION]... FILE...

Examples

Edit protected file

$ sudoedit /etc/hosts

getent

Get entries from administrative database.

General

Syntax

getent [OPTION]... DATABASE [KEY]...

Common Options

Option	Description
`-s`	Service
`-i`	Ignore case

Examples

Get users

$ getent passwd

Get groups

$ getent group

ulimit

Display/set user resource limits.

User Management

Syntax

ulimit [OPTION]... [LIMIT]

Common Options

Option	Description
`-a`	All limits
`-n`	Open files
`-u`	Processes
`-f`	File size

Examples

Show limits

$ ulimit -a

Set open files

$ ulimit -n 4096

lsof

List open files and processes.

File Management

Syntax

lsof [OPTION]...

Common Options

Option	Description
`-i`	Network
`-u`	User
`-p`	PID
`-n`	No DNS

Examples

List open files

$ lsof

List network connections

$ lsof -i

fuser

Identify processes using files.

File Management

Syntax

fuser [OPTION]... FILE...

Common Options

Option	Description
`-v`	Verbose
`-k`	Kill processes
`-m`	Mounted filesystem
`-n`	Namespace

Examples

Find process using file

$ fuser file.txt

Kill processes

$ fuser -k file.txt

lslocks

List file locks.

File Management

Syntax

lslocks [OPTION]...

Common Options

Option	Description
`-p`	PID
`-u`	User
`-n`	Sort numeric

Examples

List file locks

$ lslocks

lsns

List Linux namespaces.

General

Syntax

lsns [OPTION]...

Common Options

Option	Description
`-t`	Type
`-p`	PID
`-u`	User

Examples

List namespaces

$ lsns

nsenter

Run command in namespace.

General

Syntax

nsenter [OPTION]... [COMMAND]

Common Options

Option	Description
`-t`	PID
`-n`	Network
`-u`	UTS
`-p`	PID namespace

Examples

Enter network namespace

$ nsenter -t 1234 -n ip addr

unshare

Run program in new namespace.

General

Syntax

unshare [OPTION]... [COMMAND]

Common Options

Option	Description
`-n`	Network
`-u`	UTS
`-p`	PID
`-m`	Mount

Examples

Run in new network namespace

$ unshare -n bash

chroot

Change root directory.

File Management

Syntax

chroot [OPTION]... NEWROOT [COMMAND]

Common Options

Option	Description
`--userspec`	User/group
`--groups`	Groups

Examples

Change root

$ sudo chroot /newroot bash

pivot_root

Change system root for initrd.

System Admin

Syntax

pivot_root [OPTION]... NEWROOT PUTOLD

Common Options

Option	Description
`-h`	Help

Examples

Pivot root

$ sudo pivot_root /newroot /oldroot

mountpoint

Check if directory is mount point.

File Management

Syntax

mountpoint [OPTION]... DIRECTORY

Common Options

Option	Description
`-d`	Print device number
`-x`	Print mount point

Examples

Check mount

$ mountpoint /mnt

modprobe

Load kernel modules.

System Admin

Syntax

modprobe [OPTION]... MODULE

Common Options

Option	Description
`-r`	Remove module
`-a`	Load multiple
`-n`	Dry run
`-v`	Verbose

Examples

Load module

$ sudo modprobe module_name

Remove

$ sudo modprobe -r module_name

insmod

Insert kernel module.

System Admin

Syntax

insmod [OPTION]... MODULE [SYMBOL=VALUE]...

Examples

Insert module

$ sudo insmod module.ko

rmmod

Remove kernel module.

File Management

Syntax

rmmod [OPTION]... MODULE

Common Options

Option	Description
`-f`	Force
`-s`	Print to syslog

Examples

Remove module

$ sudo rmmod module_name

lsmod

List loaded kernel modules.

udevadm [OPTION]... COMMAND

Common Options

Option	Description
`info`	Query device info
`monitor`	Monitor events
`trigger`	Trigger events
`settle`	Wait for events

Examples

Get device info

$ udevadm info -q path /dev/sda

Monitor events

$ sudo udevadm monitor

lsinitramfs

List initramfs archive content.

Archiving

Syntax

lsinitramfs [OPTION]... [INITRAMFS]

Common Options

Option	Description
`-l`	Long format
`-v`	Verbose

Examples

List initramfs

$ lsinitramfs /boot/initrd.img-$(uname -r)

mkinitcpio

Build initramfs images (Arch).

General

Syntax

mkinitcpio [OPTION]...

Common Options

Option	Description
`-P`	All presets
`-p`	Specific preset
`-g`	Output file
`-s`	Save report

Examples

Build initramfs

$ sudo mkinitcpio -p linux

dracut

Build initramfs (Fedora/RHEL).

General

Syntax

dracut [OPTION]... [INITRAMFS] [KERNELVERSION]

Common Options

Option	Description
`-f`	Force rebuild
`-v`	Verbose
`-m`	Add module
`-o`	Omit module

Examples

Build initramfs

$ sudo dracut -f

grub-install

Install GRUB bootloader.

General

Syntax

grub-install [OPTION]... DEVICE

Common Options

Option	Description
`--root-directory`	Root directory
`--target`	Platform
`--recheck`	Recheck device map
`--boot-directory`	Boot directory

Examples

Install GRUB

$ sudo grub-install /dev/sda

grub-mkconfig

Generate GRUB configuration.

General

Syntax

grub-mkconfig [OPTION]...

Common Options

Option	Description
`-o`	Output file
`--root-directory`	Root directory

Examples

Generate config

$ sudo grub-mkconfig -o /boot/grub/grub.cfg

update-grub

Update GRUB configuration (Debian/Ubuntu).

xrandr [OPTION]...

Common Options

Option	Description
`--output`	Output name
`--mode`	Resolution
`--auto`	Auto-configure
`--right-of`	Position

Examples

List displays

$ xrandr

Set resolution

$ xrandr --output HDMI-1 --mode 1920x1080

xinput

Configure X input devices.

General

Syntax

xinput [OPTION]...

Common Options

Option	Description
`list`	List devices
`set-prop`	Set property
`disable`	Disable device
`enable`	Enable device

Examples

List input devices

$ xinput list

xset

Set X server preferences.

General

Syntax

xset [OPTION]...

Common Options

Option	Description
`b`	Bell
`s`	Screensaver
`dpms`	Display power management

Examples

Disable screensaver

$ xset s off

xprop

Display X window properties.

General

Syntax

xprop [OPTION]...

Common Options

Option	Description
`-root`	Root window
`-id`	Window ID
`-name`	Window name
`-format`	Format

Examples

Get window info

$ xprop

xev

Display X events.

General

Syntax

xev [OPTION]...

Common Options

Option	Description
`-display`	Display
`-name`	Window name

Examples

Monitor events

$ xev

xrdb

Manage X resource database.

General

Syntax

xrdb [OPTION]... [FILE]

Common Options

Option	Description
`-query`	Show resources
`-merge`	Merge resources
`-load`	Load resources

Examples

Load X resources

$ xrdb -merge ~/.Xresources

xdpyinfo

Display X server information.

General

Syntax

xdpyinfo [OPTION]...

Common Options

Option	Description
`-display`	Display
`-query`	Query extensions

Examples

Get X info

$ xdpyinfo

xdg-open

Open file with default application.

File Management

Syntax

xdg-open [OPTION]... FILE

Examples

Open file

$ xdg-open document.pdf

Open URL

$ xdg-open https://google.com

xdg-mime

Query/manage MIME associations.

General

Syntax

xdg-mime [OPTION]... COMMAND [FILE]

Common Options

Option	Description
`query`	Query default
`default`	Set default

Examples

Get default app

$ xdg-mime query default application/pdf

notify-send

Send desktop notifications.

General

Syntax

notify-send [OPTION]... [SUMMARY] [BODY]

Common Options

Option	Description
`-u`	Urgency
`-t`	Timeout
`-i`	Icon

Examples

Send notification

$ notify-send "Title" "Message"

zenity

Display GNOME dialog boxes.

General

Syntax

zenity [OPTION]...

Common Options

Option	Description
`--info`	Info dialog
`--question`	Question
`--entry`	Text input
`--file-selection`	File picker

Examples

Show info

$ zenity --info --text="Hello"

yad

GTK dialog boxes (zenity fork).

General

Syntax

yad [OPTION]...

Common Options

Option	Description
`--info`	Info
`--question`	Question
`--form`	Form
`--calendar`	Calendar

Examples

Show dialog

$ yad --info --text="Hello"

ffmpeg

Convert and process multimedia.

System Admin

Syntax

ffmpeg [OPTION]... [INPUT] [OUTPUT]

Common Options

Option	Description
`-i`	Input file
`-c`	Codec
`-b`	Bitrate
`-s`	Size
`-r`	Frame rate

Examples

Convert video

$ ffmpeg -i input.mp4 output.avi

Extract audio

$ ffmpeg -i video.mp4 -q:a 0 audio.mp3

ffplay

Simple media player.

General

Syntax

ffplay [OPTION]... [INPUT]

Common Options

Option	Description
`-i`	Input
`-window_title`	Title
`-fs`	Full screen

Examples

Play video

$ ffplay video.mp4

ffprobe

Display media file information.

File Management

Syntax

ffprobe [OPTION]... [INPUT]

Common Options

Option	Description
`-show_format`	Show format
`-show_streams`	Show streams
`-v`	Verbose

Examples

Get media info

$ ffprobe video.mp4

imagemagick

Image manipulation suite.

Networking

Syntax

convert [OPTION]... [INPUT] [OUTPUT]

Common Options

Option	Description
`-resize`	Resize
`-rotate`	Rotate
`-quality`	Quality
`-format`	Output format

Examples

Resize image

$ convert input.jpg -resize 50% output.jpg

convert

Convert image format.

General

Syntax

convert [OPTION]... [INPUT] [OUTPUT]

Common Options

Option	Description
`-resize`	Resize
`-rotate`	Rotate
`-crop`	Crop
`-quality`	Quality

Examples

Convert to PNG

$ convert image.jpg image.png

mogrify

Batch process images.

System Admin

Syntax

mogrify [OPTION]... [INPUT]...

Common Options

Option	Description
`-resize`	Resize
`-format`	Format
`-quality`	Quality

Examples

Resize all images

$ mogrify -resize 50% *.jpg

exiftool

Read/write metadata.

General

Syntax

exiftool [OPTION]... [FILE]

Common Options

Option	Description
`-a`	All tags
`-r`	Recursive
`-o`	Output file

Examples

Read metadata

$ exiftool image.jpg

mediainfo

Display media file information.

File Management

Syntax

mediainfo [OPTION]... [FILE]

Common Options

Option	Description
`-f`	Full output

Examples

Get media info

$ mediainfo video.mp4

sox

Sound processing tool.

System Admin

Syntax

sox [OPTION]... [INPUT] [OUTPUT]

Common Options

Option	Description
`-r`	Sample rate
`-b`	Bit depth
`-c`	Channels
`trim`	Trim audio

Examples

Convert audio

$ sox input.wav output.mp3

pactl

Control PulseAudio.

General

Syntax

pactl [OPTION]... COMMAND

Common Options

Option	Description
`list`	List objects
`set-sink-volume`	Set volume
`set-sink-mute`	Mute

Examples

List sinks

$ pactl list sinks

Set volume

$ pactl set-sink-volume 0 50%

amixer

ALSA mixer control.

General

Syntax

amixer [OPTION]... COMMAND

Common Options

Option	Description
`scontrols`	Show controls
`sget`	Get control
`sset`	Set control

Examples

Set volume

$ amixer set Master 50%

alsamixer

ALSA mixer GUI.

General

Syntax

alsamixer [OPTION]...

Common Options

Option	Description
`-c`	Card
`-V`	View

Examples

Start mixer

$ alsamixer

speaker-test

Test audio output.

General

Syntax

speaker-test [OPTION]...

Common Options

Option	Description
`-t`	Test type
`-c`	Channels
`-f`	Frequency
`-l`	Loops

Examples

Test speakers

$ speaker-test -t wav

arecord

ALSA audio recorder.

General

Syntax

arecord [OPTION]... [FILE]

Common Options

Option	Description
`-f`	Format
`-r`	Sample rate
`-d`	Duration
`-c`	Channels

Examples

Record audio

$ arecord -d 10 test.wav

aplay

ALSA audio player.

General

Syntax

aplay [OPTION]... [FILE]

Common Options

Option	Description
`-f`	Format
`-r`	Sample rate
`-D`	Device

Examples

Play audio

$ aplay test.wav

bluetoothctl

Control Bluetooth devices.

General

Syntax

bluetoothctl [OPTION]... [COMMAND]

Common Options

Option	Description
`power`	Power on/off
`scan`	Scan for devices
`pair`	Pair device
`connect`	Connect device

Examples

Start Bluetooth

$ bluetoothctl power on

Scan devices

$ bluetoothctl scan on

hciconfig

Configure Bluetooth devices.

General

Syntax

hciconfig [OPTION]... [DEVICE]

Common Options

Option	Description
`up`	Enable
`down`	Disable
`hci`	HCI commands

Examples

Show devices

$ hciconfig -a

rfkill

Enable/disable wireless devices.

General

Syntax

rfkill [OPTION]... COMMAND

Common Options

Option	Description
`list`	List devices
`block`	Block device
`unblock`	Unblock device

Examples

List devices

$ rfkill list

Enable Wi-Fi

$ rfkill unblock wifi

lsmem

List memory blocks.

System Admin

Syntax

lsmem [OPTION]...

Common Options

Option	Description
`--summary`	Summary
`--all`	All blocks

Examples

Show memory info

$ lsmem

lshw

Detailed hardware information.

General

Syntax

lshw [OPTION]...

Common Options

Option	Description
`-short`	Short output
`-html`	HTML output
`-xml`	XML output
`-C`	Class

Examples

List hardware

$ sudo lshw

Summary

$ sudo lshw -short

smartctl

Monitor SMART data on drives.

General

Syntax

smartctl [OPTION]... DEVICE

Common Options

Option	Description
`-a`	All info
`-H`	Health status
`-t`	Test
`-l`	Log

Examples

Check health

$ sudo smartctl -H /dev/sda

Show all info

$ sudo smartctl -a /dev/sda

hdparm

Get/set hard drive parameters.

General

Syntax

hdparm [OPTION]... DEVICE

Common Options

Option	Description
`-I`	Identify info
`-t`	Read speed test
`-T`	Cache test
`-S`	Standby timeout

Examples

Get drive info

$ sudo hdparm -I /dev/sda

Test read speed

$ sudo hdparm -t /dev/sda

nvme

Manage NVMe drives.

General

Syntax

nvme [OPTION]... COMMAND [DEVICE]

Common Options

Option	Description
`list`	List devices
`id-ctrl`	Controller info
`smart-log`	SMART data

Examples

List NVMe drives

$ sudo nvme list

SMART info

$ sudo nvme smart-log /dev/nvme0

sensors

Read hardware sensors.

General

Syntax

sensors [OPTION]...

Common Options

Option	Description
`-A`	All chips
`-u`	Raw output
`-j`	JSON output

Examples

Read sensors

$ sensors

lm_sensors

Hardware sensor configuration.

General

Syntax

sensors-detect [OPTION]...

Common Options

Option	Description
`--auto`	Auto-detect

Examples

Detect sensors

$ sudo sensors-detect

turbostat

Report CPU frequency and power.

System Admin

Syntax

turbostat [OPTION]...

Common Options

Option	Description
`-c`	CPU
`-v`	Verbose
`-q`	Quiet

Examples

Monitor CPU

$ sudo turbostat

cpupower

CPU power management tool.

System Admin

Syntax

cpupower [OPTION]... COMMAND

Common Options

Option	Description
`frequency`	Manage frequency
`idle`	Idle states
`monitor`	Monitor stats

Examples

Set frequency governor

$ sudo cpupower frequency-set -g performance

stress

Simple stress testing tool.

General

Syntax

stress [OPTION]...

Common Options

Option	Description
`-c`	CPU workers
`-m`	Memory workers
`-d`	Disk workers
`-i`	I/O workers

Examples

Stress CPU

$ stress -c 4

stress-ng

Advanced system stress tester.

System Admin

Syntax

stress-ng [OPTION]...

Common Options

Option	Description
`--cpu`	CPU stress
`--vm`	Memory stress
`--hdd`	Disk stress
`--timeout`	Time limit

Examples

Stress all

$ stress-ng --cpu 4 --timeout 60s

fio

Flexible I/O tester.

General

Syntax

fio [OPTION]... [JOBFILE]

Common Options

Option	Description
`--rw`	Read/write type
`--bs`	Block size
`--size`	Test size
`--runtime`	Runtime

Examples

Benchmark

$ fio --name=test --rw=read --size=1G

bonnie++

Filesystem benchmark.

File Management

Syntax

bonnie++ [OPTION]...

Common Options

Option	Description
`-d`	Directory
`-s`	File size
`-n`	Number of files

Examples

Run benchmark

$ bonnie++ -d /tmp -s 1G

sysbench

System benchmark tool.

System Admin

Syntax

sysbench [OPTION]... COMMAND

Common Options

Option	Description
`--test`	Test type
`--cpu`	CPU test
`--memory`	Memory test
`--fileio`	File I/O test

Examples

CPU test

$ sysbench cpu run

Memory test

$ sysbench memory run

git

Distributed version control system.

System Admin

Syntax

git [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`init`	Create repository
`clone`	Clone repository
`add`	Add files
`commit`	Commit changes
`push`	Push to remote
`pull`	Pull from remote
`status`	Show status
`log`	Show history

Examples

Initialize repo

$ git init

Clone repo

$ git clone https://github.com/user/repo.git

Add and commit

$

git add .
git commit -m "Message"

gitk

Git repository browser.

General

Syntax

gitk [OPTION]...

Common Options

Option	Description
`--all`	Show all branches

Examples

Open gitk

$ gitk

tig

Git text-mode interface.

Text Processing

Syntax

tig [OPTION]...

Common Options

Option	Description
`status`	Show status
`log`	Show log
`diff`	Show diff

Examples

Launch tig

$ tig

svn

Subversion version control.

General

Syntax

svn [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`co`	Checkout
`add`	Add files
`commit`	Commit
`update`	Update
`log`	Show logs

Examples

Checkout

$ svn co https://svn.example.com/repo

Commit

$ svn commit -m "Message"

hg

Mercurial version control.

General

Syntax

hg [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`init`	Init repository
`add`	Add files
`commit`	Commit
`push`	Push
`pull`	Pull
`log`	Show history

Examples

Init

$ hg init

Commit

$ hg commit -m "Message"

cvs

Concurrent Versions System.

System Admin

Syntax

cvs [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`checkout`	Checkout
`update`	Update
`commit`	Commit
`add`	Add file

Examples

Checkout

$ cvs checkout repo

make

Build automation tool.

General

Syntax

make [OPTION]... [TARGET]...

Common Options

Option	Description
`-j`	Jobs
`-f`	Makefile
`-C`	Directory
`-n`	Dry run

Examples

Build

$ make

With 4 jobs

$ make -j4

cmake

Cross-platform build system.

System Admin

Syntax

cmake [OPTION]... [SOURCE]

Common Options

Option	Description
`-B`	Build directory
`-D`	Define variable
`-G`	Generator

Examples

Configure

$ cmake -B build -DCMAKE_BUILD_TYPE=Release

Build

$ cmake --build build

meson

Meson build system.

System Admin

Syntax

meson [OPTION]... [COMMAND]

Common Options

Option	Description
`setup`	Configure
`compile`	Build
`install`	Install
`test`	Run tests

Examples

Configure

$ meson setup build

Build

$ ninja -C build

ninja

Small build system.

System Admin

Syntax

ninja [OPTION]... [TARGET]

Common Options

Option	Description
`-C`	Directory
`-j`	Jobs
`-t`	Tools

Examples

Build

$ ninja

With 4 jobs

$ ninja -j4

gcc

Compile C programs.

General

Syntax

gcc [OPTION]... [FILE]...

Common Options

Option	Description
`-o`	Output file
`-Wall`	Warnings
`-g`	Debug info
`-O`	Optimization
`-I`	Include path

Examples

Compile

$ gcc -o program program.c

g++

Compile C++ programs.

General

Syntax

g++ [OPTION]... [FILE]...

Common Options

Option	Description
`-o`	Output
`-std`	Standard
`-Wall`	Warnings

Examples

Compile C++

$ g++ -std=c++17 -o program program.cpp

clang

LLVM C compiler.

General

Syntax

clang [OPTION]... [FILE]...

Common Options

Option	Description
`-o`	Output
`-Wall`	Warnings
`-g`	Debug

Examples

Compile

$ clang -o program program.c

clang++

LLVM C++ compiler.

General

Syntax

clang++ [OPTION]... [FILE]...

Common Options

Option	Description
`-o`	Output
`-std`	Standard

Examples

Compile C++

$ clang++ -std=c++17 -o program program.cpp

gdb

GNU source-level debugger.

General

Syntax

gdb [OPTION]... [PROGRAM]

Common Options

Option	Description
`-p`	Attach to PID
`-c`	Core file
`-x`	Commands file

Examples

Debug program

$ gdb ./program

lldb

LLVM debugger.

General

Syntax

lldb [OPTION]... [PROGRAM]

Common Options

Option	Description
`-p`	Attach to PID
`-c`	Core file
`-o`	Command

Examples

Debug program

$ lldb ./program

objdump

Display object file info.

File Management

Syntax

objdump [OPTION]... [FILE]

Common Options

Option	Description
`-d`	Disassemble
`-t`	Symbols
`-h`	Section headers

Examples

Disassemble

$ objdump -d program

nm

Display symbol table.

General

Syntax

nm [OPTION]... [FILE]

Common Options

Option	Description
`-a`	All symbols
`-g`	Global only
`-S`	Size

Examples

List symbols

$ nm program

readelf

Display ELF file info.

File Management

Syntax

readelf [OPTION]... [FILE]

Common Options

Option	Description
`-h`	Header
`-S`	Sections
`-s`	Symbols

Examples

Read ELF

$ readelf -h program

strip

Strip symbols from binary.

Networking

Syntax

strip [OPTION]... [FILE]

Common Options

Option	Description
`-s`	Strip all
`-g`	Strip debugging
`-o`	Output file

Examples

Strip binary

$ strip program

objcopy

Copy/convert object files.

File Management

Syntax

objcopy [OPTION]... [INPUT] [OUTPUT]

Common Options

Option	Description
`-O`	Output format
`-j`	Section
`--strip`	Strip sections

Examples

Copy object

$ objcopy input.o output.o

addr2line

Convert address to source line.

General

Syntax

addr2line [OPTION]... [ADDRESS]...

Common Options

Option	Description
`-e`	Executable
`-f`	Function name
`-p`	Pretty print

Examples

Convert address

$ addr2line -e program 0x123456

size

Show section sizes.

General

Syntax

size [OPTION]... [FILE]

Common Options

Option	Description
`-A`	Berkeley format
`-B`	SysV format
`-d`	Decimal

Examples

Show sizes

$ size program

jq

Process JSON data.

System Admin

Syntax

jq [OPTION]... [FILTER] [FILE]

Common Options

Option	Description
`-r`	Raw output
`-c`	Compact output
`-f`	Filter file

Examples

Parse JSON

$ jq '.key' file.json

Pretty print

$ jq '.' file.json

yq

Process YAML data.

System Admin

Syntax

yq [OPTION]... [COMMAND] [FILE]

Common Options

Option	Description
`eval`	Evaluate expression
`-i`	In-place edit
`-y`	YAML output

Examples

Extract value

$ yq eval '.key' file.yaml

xmlstarlet

Process XML data.

System Admin

Syntax

xmlstarlet [OPTION]... COMMAND [FILE]

Common Options

Option	Description
`sel`	Select
`ed`	Edit
`tr`	Transform

Examples

Parse XML

$ xmlstarlet sel -t -v "/root/key" file.xml

sqlite3

SQLite database shell.

User Management

Syntax

sqlite3 [OPTION]... [DBFILE] [SQL]

Common Options

Option	Description
`-header`	Show headers
`-list`	List mode
`-csv`	CSV output

Examples

Open database

$ sqlite3 database.db

Run query

$ sqlite3 database.db "SELECT * FROM table;"

mysql

MySQL database client.

General

Syntax

mysql [OPTION]... [DATABASE]

Common Options

Option	Description
`-u`	User
`-p`	Password
`-h`	Host
`-e`	Execute query

Examples

Connect

$ mysql -u root -p

Run query

$ mysql -u root -p -e "SHOW DATABASES;"

mariadb

MariaDB database client.

General

Syntax

mariadb [OPTION]... [DATABASE]

Common Options

Option	Description
`-u`	User
`-p`	Password
`-h`	Host

Examples

Connect

$ mariadb -u root -p

psql

PostgreSQL interactive terminal.

General

Syntax

psql [OPTION]... [DATABASE]

Common Options

Option	Description
`-U`	User
`-h`	Host
`-d`	Database
`-c`	Execute command

Examples

Connect

$ psql -U username -d database

Run query

$ psql -c "SELECT * FROM table;"

redis-cli

Redis command-line client.

General

Syntax

redis-cli [OPTION]... [COMMAND]

Common Options

Option	Description
`-h`	Host
`-p`	Port
`-a`	Password
`--scan`	Scan keys

Examples

Connect

$ redis-cli

Run command

$ redis-cli SET key value

mongosh

MongoDB shell.

User Management

Syntax

mongosh [OPTION]... [CONNECTION]

Common Options

Option	Description
`--host`	Host
`--port`	Port
`-u`	User
`-p`	Password

Examples

Connect

$ mongosh "mongodb://localhost:27017"

php

PHP command-line interpreter.

General

Syntax

php [OPTION]... [FILE]

Common Options

Option	Description
`-a`	Interactive
`-r`	Execute code
`-f`	File
`-m`	Modules

Examples

Run file

$ php script.php

Execute code

$ php -r "echo 'Hello';"

python

Python programming language.

General

Syntax

python [OPTION]... [FILE]

Common Options

Option	Description
`-c`	Execute code
`-m`	Module
`-i`	Interactive
`-v`	Verbose

Examples

Run script

$ python script.py

Interactive

$ python -i

python3

Python 3 interpreter.

General

Syntax

python3 [OPTION]... [FILE]

Common Options

Option	Description
`-c`	Execute code
`-m`	Module
`-v`	Verbose

Examples

Run script

$ python3 script.py

pip

Python package installer.

General

Syntax

pip [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`install`	Install package
`uninstall`	Uninstall
`list`	List packages
`freeze`	Freeze requirements

Examples

Install package

$ pip install package

List packages

$ pip list

pip3

Python 3 package manager.

General

Syntax

pip3 [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`install`	Install
`list`	List
`freeze`	Requirements

Examples

Install

$ pip3 install package

node

Node.js JavaScript runtime.

Networking

Syntax

node [OPTION]... [FILE]

Common Options

Option	Description
`-v`	Version
`-e`	Execute code
`-r`	Module

Examples

Run script

$ node script.js

REPL

$ node

npm

Node.js package manager.

General

Syntax

npm [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`install`	Install packages
`uninstall`	Uninstall
`init`	Initialize project
`start`	Start script
`test`	Run tests

Examples

Install

$ npm install package

Start

$ npm start

npx

Execute Node packages.

General

Syntax

npx [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`--package`	Package
`-q`	Quiet

Examples

Run package

$ npx create-react-app app

yarn

Yarn JavaScript package manager.

Networking

Syntax

yarn [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`add`	Add package
`remove`	Remove package
`install`	Install dependencies
`start`	Start script
`test`	Run tests

Examples

Add package

$ yarn add package

Start

$ yarn start

pnpm

Fast, disk-efficient package manager.

Disk Usage

Syntax

pnpm [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`add`	Add package
`install`	Install
`remove`	Remove
`start`	Start script

Examples

Add package

$ pnpm add package

deno

Modern JavaScript/TypeScript runtime.

Networking

Syntax

deno [OPTION]... [FILE]

Common Options

Option	Description
`run`	Run script
`test`	Test
`fmt`	Format
`lint`	Lint

Examples

Run script

$ deno run script.ts

bun

JavaScript runtime and toolkit.

Networking

Syntax

bun [OPTION]... [FILE]

Common Options

Option	Description
`run`	Run script
`test`	Test
`install`	Install packages
`start`	Start script

Examples

Run script

$ bun run script.js

java

Java application launcher.

General

Syntax

java [OPTION]... [CLASS]

Common Options

Option	Description
`-version`	Version
`-cp`	Classpath
`-jar`	JAR file
`-X`	VM options

Examples

Run JAR

$ java -jar app.jar

Run class

$ java MyClass

javac

Java source compiler.

General

Syntax

javac [OPTION]... [FILE]...

Common Options

Option	Description
`-d`	Output directory
`-cp`	Classpath
`-source`	Source version
`-target`	Target version

Examples

Compile

$ javac MyClass.java

jshell

Java REPL.

General

Syntax

jshell [OPTION]... [FILE]

Common Options

Option	Description
`--class-path`	Classpath
`-v`	Verbose

Examples

Start REPL

$ jshell

kotlin

Kotlin application launcher.

General

Syntax

kotlin [OPTION]... [FILE]

Examples

Run script

$ kotlin script.kts

rustc

Rust programming language compiler.

General

Syntax

rustc [OPTION]... [FILE]

Common Options

Option	Description
`-o`	Output
`-C`	Codegen options
`-L`	Library path

Examples

Compile

$ rustc main.rs

cargo

Rust's build system and package manager.

System Admin

Syntax

cargo [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`build`	Build project
`run`	Run project
`test`	Run tests
`add`	Add dependency
`new`	New project
`init`	Init project

Examples

New project

$ cargo new myproject

Build

$ cargo build

Run

$ cargo run

go

Go programming language tool.

General

Syntax

go [OPTION]... COMMAND [ARGUMENT]...

Common Options

Option	Description
`run`	Run program
`build`	Build program
`mod`	Module management
`test`	Run tests
`get`	Download packages

Examples

Run

$ go run main.go

Build

$ go build

perl

Perl programming language.

General

Syntax

perl [OPTION]... [FILE]

Common Options

Option	Description
`-e`	Execute code
`-n`	Loop over input
`-p`	Loop and print
`-i`	In-place edit

Examples

Run script

$ perl script.pl

Execute command

$ perl -e 'print "Hello\n"'

ruby

Ruby programming language.

General

Syntax

ruby [OPTION]... [FILE]

Common Options

Option	Description
`-e`	Execute code
`-c`	Syntax check
`-v`	Verbose
`-w`	Warnings

Examples

Run script

$ ruby script.rb

lua

Lua programming language.

General

Syntax

lua [OPTION]... [FILE]

Common Options

Option	Description
`-e`	Execute code
`-l`	Load library
`-i`	Interactive

Examples

Run script

$ lua script.lua

R

R statistical computing.

General

Syntax

R [OPTION]... [FILE]

Common Options

Option	Description
`-e`	Execute expression
`-f`	File
`--vanilla`	No save/restore

Examples

Run script

$ Rscript script.R

octave

GNU Octave numerical computation.

General

Syntax

octave [OPTION]... [FILE]

Common Options

Option	Description
`--eval`	Execute code
`--no-gui`	Command line
`-q`	Quiet

Examples

Run script

$ octave script.m

tldr

Simplified command documentation.

General

Syntax

tldr [OPTION]... COMMAND

Common Options

Option	Description
`-u`	Update cache
`-p`	Platform
`-l`	List commands

Examples

Get help for ls

$ tldr ls

tree

Display directory tree.

File Management

Syntax

tree [OPTION]... [DIRECTORY]

Common Options

Option	Description
`-L`	Depth
`-d`	Directories only
`-f`	Full path
`-h`	Human readable

Examples

Show tree

$ tree

Limited depth

$ tree -L 2

watchman

Watch files and directories.

File Management

Syntax

watchman [OPTION]... COMMAND

Common Options

Option	Description
`watch`	Watch directory
`trigger`	Trigger command
`since`	Changes since

Examples

Watch directory

$ watchman watch /path

bat

Syntax-highlighted file viewer.

File Management

Syntax

bat [OPTION]... [FILE]

Common Options

Option	Description
`-A`	Show non-printable
`-n`	Number lines
`-p`	Plain output
`-l`	Language

Examples

View file

$ bat file.txt