Bash Commands

uname -a Show system and kernel
head -n1 /etc/issue Show distri­bution
mount Show mounted filesy­stems
date Show system date
uptime Show uptime
whoami Show your username
man command Show manual for command

Bash Shortcuts

CTRL-c Stop current command
CTRL-z Sleep program
CTRL-a Go to start of line
CTRL-e Go to end of line
CTRL-u Cut from start of line
CTRL-k Cut to end of line
CTRL-r Search history
!! Repeat last command
!abc Run last command starting with abc
!abc:p Print last command starting with abc
!$ Last argument of previous command
ALT-. Last argument of previous command
!* All arguments of previous command
^abc^123 Run previous command, replacing abc with 123

Bash Variables

env Show enviro­nment variables
echo $NAME Output value of $NAME variable
export NAME=value Set $NAME to value
$PATH Executable search path
$HOME Home directory
$SHELL Current shell

IO Redire­ction

cmd < file

Input of cmd from file

cmd1 <(cmd2)

Output of cmd2 as file input to cmd1

cmd > file

Standard output (stdout) of cmd to file

cmd > /dev/null

Discard stdout of cmd

cmd >> file

Append stdout to file

cmd 2> file

Error output (stderr) of cmd to file

cmd 1>&2

stdout to same place as stderr

cmd 2>&1

stderr to same place as stdout

cmd &> file

Every output of cmd to file

cmd refers to a command.


cmd1 | cmd2

stdout of cmd1 to cmd2

cmd1 |& cmd2

stderr of cmd1 to cmd2

Command Lists

cmd1 ; cmd2

Run cmd1 then cmd2

cmd1 && cmd2

Run cmd2 if cmd1 is successful

cmd1 || cmd2

Run cmd2 if cmd1 is not successful

cmd &

Run cmd in a subshell

Directory Operations

pwd Show current directory
mkdir dir Make directory dir
cd dir Change directory to dir
cd .. Go up a directory
ls List files

ls Options

-a Show all (including hidden)
-R Recursive list
-r Reverse order
-t Sort by last modified
-S Sort by file size
-l Long listing format
-1 One file per line
-m Comma-­sep­arated output
-Q Quoted output

Search Files

grep pattern files Search for pattern in files
grep -i Case insens­itive search
grep -r Recursive search
grep -v Inverted search
grep -o Show matched part of file only
find /dir/ -name name* Find files starting with name in dir
find /dir/ -user name Find files owned by name in dir
find /dir/ -mmin num Find files modifed less than num minutes ago in dir
whereis command Find binary / source / manual for command
locate file Find file (quick search of system index)

File Operations

touch file1

Create file1

cat file1 file2

Concat­enate files and output

less file1

View and paginate file1

file file1

Get type of file1

cp file1 file2

Copy file1 to file2

mv file1 file2

Move file1 to file2

rm file1

Delete file1

head file1

Show first 10 lines of file1

tail file1

Show last 10 lines of file1

tail -F file1

Output last lines of file1 as it changes

Watch a Command

watch -n 5 ‘ntpq -p’

Issue the ‘ntpq -p’ command every 5 seconds and display output

Process Management

ps Show snapshot of processes
top Show real time processes
kill pid Kill process with id pid
pkill name Kill process with name name
killall name Kill all processes with names beginning name

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