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.

Pipes

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

Nano Shortcuts

Files
Ctrl-R
Read file
Ctrl-O
Save file
Ctrl-X
Close file
Cut and Paste
ALT-A
Start marking text
CTRL-K
Cut marked text or line
CTRL-U
Paste text
Navigate File
ALT-/
End of file
CTRL-A
Beginning of line
CTRL-E
End of line
CTRL-C
Show line number
CTRL-_
Go to line number
Search File
CTRL-W
Find
ALT-W
Find next
CTRL-\
Search and replace

Screen Shortcuts

screen
Start a screen session.
screen -r
Resume a screen session.
screen -list
Show your current screen sessions.
CTRL-A
Activate commands for screen.
CTRL-A c
Create a new instance of terminal.
CTRL-A n
Go to the next instance of terminal.
CTRL-A p
Go to the previous instance of terminal.
CTRL-A “
Show current instances of terminals.
CTRL-A A
Rename the current instance.

File Permis­sions

chmod 775 file
Change mode of file to 775
chmod -R 600 folder
Recurs­ively chmod folder to 600
chown user:group file
Change file owner to user and group to group

File Permission Numbers

First digit is owner permis­sion, second is group and third is everyone.
Calculate permission digits by adding numbers below.
4
read (r)
2
write (w)