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

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 user@example.com

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@example.com"

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" user@example.com

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" user@example.com

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 user@example.com < 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" user@example.com < 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