Command Line

(command-line-cheat-sheet)=

Command-line cheat sheet

This page lists the most common commands in the Ubuntu command line. For full details on any command, run man <command> in your terminal.

CLI basics

More detailed explanation of the commands in this section can be found in our {ref}welcome-to-the-terminal tutorial.

Navigation

Command	Description	Online manual page
pwd	Print the current working directory	{manpage}pwd(1)
ls	List all files and directories in the current directory	{manpage}ls(1)
ls -l	Long list, with permissions, owner, size, and date
ls -a	List all, including hidden files (file names starting with .)
ls -la or ll	Long listing including hidden files
ls -ld <dir>	Show the directory entry itself, not its contents, for directory <dir>
ls -l <file>	Show file type, permissions, owner, and size for <file>
cd <path>	Change to the specified directory	cd(1posix)
cd ..	Move up to the parent directory
cd ~	Return to the home directory
cd -	Return to the previous directory
cd /	Move to the root directory
cd ../../	Move up two levels at once

Working with the filesystem

Command	Description	Online manual page
mkdir <name>	Create a new directory	{manpage}mkdir(1)
rmdir <name>	Remove an empty directory	{manpage}rmdir(1)
tree	Display directory structure as a tree	{manpage}tree(1)
tree -L <n> <path>	Display tree to depth n

Working with files

Command	Description	Online manual page
touch <file>	Create a new (empty) file, or update the timestamp of an existing file	{manpage}touch(1)
cp <src> <dest>	Copy a file from a source (src) to a new destination (dest)	{manpage}cp(1)
cp -a <src> <dest>	Copy a directory recursively, preserving permissions
mv <src> <dest>	Rename a file or directory	{manpage}mv(1)
mv <src>/file <dest>/file	Move a file without renaming it
rm <file>	Remove a file	{manpage}rm(1)
rm -r <dir>	Remove a non-empty directory and all its contents
cat <file>	Print the contents of <file> to the screen	{manpage}cat(1)
less <file>	View file contents one page at a time	{manpage}less(1)
head -n 20 <file>	Print the first 20 lines of a file (default with no flag is 10)	{manpage}head(1)
tail -n 20 <file>	Print the last 20 lines of a file (default with no flag is 10)	{manpage}tail(1)
wc -l <file>	Count the number of lines in a file	{manpage}wc(1)

Users, groups, and permissions

Command	Description	Online manual page
chmod <mode> <file>	Change file permissions (symbolic or numeric notation)	{manpage}chmod(1)
chown <user>:<group> <file>	Change file owner and group	{manpage}chown(1)
umask	Show or set the default permissions mask	{manpage}umask(2)
sudo <command>	Run a command with administrator privileges	{manpage}sudo(8) <sudo-rs(8)>

Searching

Command	Description	Online manual page
grep <pattern> <file>	Search for lines matching a pattern in a file	{manpage}grep(1)
grep <name> /etc/passwd	Look up a user account
grep <name> /etc/group	Look up group membership
find <path> -name <pattern>	Search for files matching a name pattern	{manpage}find(1)
which <command>	Show the full path to an executable command	{manpage}which(1) <which.debianutils(1)>
file <name>	Determine the type of a file	{manpage}file(1)

CLI in depth

More detailed explanation of the commands and operators in this section can be found in our {ref}cli-in-depth tutorial.

Redirecting input and output

| Command | Description | | —————– | —————————————————————————–– | — | | cmd > file | Redirect stdout (1) to a file (overwrites existing content) | | | cmd >> file | Append stdout (1) to the end of <file> (does not overwrite existing contents) | | | cmd < file | Pass a file’s contents as stdin (0) to a command (cmd) | | | cmd > /dev/null | Discard stdout (1) entirely | | | cmd 2> file | Redirect stderr (2) to a file | | | cmd > file 2>&1 | Redirect both stdout (1) and stderr (2) to a file | | | cmd << EOF | Here-document: feed multi-line text as stdin, ended by a line containing EOF | |

Pipes and command chaining

Command	Description
cmd1 | cmd2	Pipe stdout (1) of cmd1 to stdin (0) of cmd2
cmd1; cmd2	Run commands in sequence regardless of exit status
cmd1 && cmd2	Run cmd2 only if cmd1 succeeds (exit code 0)
cmd1 || cmd2	Run cmd2 only if cmd1 fails (non-zero exit code)
cmd &	Run a command in the background
{ cmd1; cmd2; } > file	Group commands and redirect their combined output
(cmd1; cmd2)	Run commands in a subshell (side effects don’t affect the current shell)
cmd1 \	Continue a long command on the next line

Variables and environment

Command	Description	Online manual page
env	List all environment variables	{manpage}env(1)
echo $VAR	Print the value of variable VAR	See note below this table
VAR=value	Set a shell variable (available in current shell only)
export VAR=value	Set a variable and export it to child processes
unset VAR	Remove a variable
echo $?	Print the exit status of the last command (0 = success)
echo $$	Print the PID of the current shell

:::{note} If you are using the bash, dash or zsh shell, echo is a builtin command documented under the shell manual page. For example, the bash builtin shell section. If your shell doesn’t have an echo builtin command, use the {manpage}echo(1) manual page instead. :::

Shell expansion

Command	Description
~	Expands to the home directory ($HOME)
$VAR, ${VAR}	Variable expansion: replaced by the value of VAR
$(command)	Command substitution: replaced by the output of command
$((expr))	Arithmetic expansion: evaluates integer arithmetic, e.g. $((5 + 3)) evaluates to 8
{a,b,c}	Brace expansion: generates separate words, e.g. {a,b,c} → a b c
{1..10}	Range expansion: generates a sequence, e.g. {1..5} → 1 2 3 4 5
*	Glob: matches any sequence of characters in a filename
?	Glob: matches any single character in a filename
[abc]	Glob: matches any one of the listed characters in a filename

Getting help

Command	Description	Online manual page
man <command>	Open the manual page for a command
man man	Open the manual page for man itself	{manpage}man(1)
man -k <keyword>	Search man page descriptions for a keyword
<command> --help	Print a brief help summary for a command