# What are your favorite command line features or tricks?

Share your command line features and tricks for Unix/Linux. Try to keep it shell/distro agnostic if possible. Interested in seeing aliases, one-liners, keyboard shortcuts, small shell scripts, etc.

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## locked by Michael Mrozek♦Nov 6 '11 at 0:41

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## 63 Answers

Display Git branch and status in the prompt

export GIT_PS1_SHOWDIRTYSTATE=true

if [ "$color_prompt" = yes ]; then PS1='${debian_chroot:+($debian_chroot)}$\033[01;32m$\u@\h$\033[00m$:$\033[01;34m$\w$\033[00m$$(__git_ps1 "#%s")\$' else PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w$(__git_ps1 "#%s")\$' fi  - Also check vcprompt: vc.gerg.ca/hg/vcprompt The same idea, and supports git, mercurial and subversion. – Sergio Acosta Aug 26 '10 at 9:13 Sometimes bash settings are such that rm is aliased to rm -i and thus requires confirmation for each file being deleted. When I work occasionally on such an account, I use \rm to retrieve the original behaviour of rm without changing user configuration. - Displays a nice ascii art of the current proccess tree, with the most cpu intensive proccess higlighted. while true; do clear; pstree$( ps -eo pid --sort %cpu | tail -n 1 );
sleep 1;
done


Kill it with Ctrl + C

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I prefer using htop ;) – André Paramés Dec 16 '10 at 14:19
Intead of loop you may use watch: watch -n 1 --no-title 'pstree $(ps -eo pid --sort %cpu | tail -n 1)' – php-coder May 25 '11 at 4:18 this gives you some insight which is not that obvious in htop or top. Cool – Ali Nov 25 '11 at 1:12 Once so often when you've typed a long command and before finishing it you've realized it won't work right away, because you need to run something else before (e.g. entered git commit -m "long commit message here"), you can hit ^A^K to go to the start of the line and kill it (saving into a buffer), next run a command to fix things, and finally ^Y to paste the killed command, and continue. Saves a lot of re-typing. All this, of course is when readline is in Emacs mode. Another time-saver: mkdir -p some/nested/dirs/to/be/created creates all the dirs in a path if they're missing. - My favourite command is 'find', I use it everywhere... examples: find . -name "*.log" -exec ls -l {} \; | grep "$(find . -name "*.log" -exec ls -l {} \;| nawk '{print $5}' | sort -n | tail )"  Just display heaviest files in ls -l (long) format. Then, if you need your code with 0640 permissions, just search: find . $$\( ! -perm 0640$$ -a $$-name "*.cpp" -o -name "*.h"$$ \) -ls | nawk '{print$3"\t"$11}'  or replace: find . $$-name "*.cpp" -o -name "*.h"$$ | xargs chmod 640  Then, do you need a symbol and don't know where is it?? ( for myObj in$(find . -name "*.o"); do
gotSym=$(dump -Xany -t$myObj | grep .MY_SYMBOL)
if ! test "x$gotSym" = "x" then echo "OBJECT [$myObj] ========================"
echo "$gotSym" echo "^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^"^ fi done )  Newer files than XFILE?? find . -newer XFILE -type f  Yeah, "find" rulez! - my favorite feature is NO COLORS! =) TERM=xterm-mono or TERM=linux-m depends on OS... I really like black and white IRSSI, mc and any other "Text user interface" tool - +1 for IRSSI :-) – Chris Aug 27 '10 at 17:25 But why? It's not the eighties anymore - give your eyes some rest and put some colors in there B=). I like having different colors to distinguish different irrsi users. – user13742 Jan 13 '12 at 0:59 ZSH has global aliases. It expands the alias anywhere in the command line. I've found this useful for hostnames: E.g.: alias -g sub='sub.domain.tld'  Then, I can do e.g.: sftp sub ssh sub  etc. - It's nice when working with bluetooth; I have E65='XX:XX:XX:XX:XX', s then I can use obex commands without having to type my phone's bluetooth address. – André Paramés Dec 16 '10 at 14:16 # change chmod to file dowloaded -->$_

wget -c http://link/to/file -O /path/to/save/namefile && chmod 0755 $_ # extract tar.bz2 or tar.gz whit less work # this avoids having to unpack and then move the files to another location, in this case have # already extracted in the desired location tar jxvf file.tar.bz2 -C /pat/to/extract # calculator with bc - in bashrc calc(){ echo "scale=2;$@" | bc;}

# set magic-space in bashrc
bind Space:magic-space                 # !pin<space>  expand last cmd pin...

# alias to open last edited file in vim
alias lvim="vim -c \"normal '0\""

# alias to show your path set
alias path='echo -e ${PATH//:/\\n}'  - See command output updated every n seconds watch -n 60 df -h (displays df -h every 60 seconds)  Show statistics about network device wlan0 ip -s link ls wlan0  Show routing table for device eth1 ip route ls dev eth1  Display statistics for all routers packet travels through to reach HOST mtr --interval 5 HOSTNAME  Consult reverse DNS records for host names on NETWORK nmap -sL NETWORK  Benchmark a website ab  Get all links from a web page lynx -dump http://www.yahoo.com | awk '/http/{print$2}'


Show default gateway

netstat -rn | awk '/UG/{print $2}'  Write standard error to a file foo 2> errors.txt  Redirect stderr to stdout foo 2>&1  Redirect both stderr and stdout to the same file. foo > file.txt 2>&1  - Replace parts of the previous command: ^search^replace $ echo a b c d
a b c d
$^b c^X echo a X d a X d  Great for typos: $ mkae
-bash: mkae: command not found
$^ka^ak make [...]  - zsh spelling correction is great for typos. ;-) – Mikel Apr 7 '11 at 8:51 When you accidentally mix two letters in command name (like in your example with make) shortcut Ctrl+t may be usefull to exchange these letters. – php-coder May 25 '11 at 4:41 Summarize directory size, with descending human size du -hs */ | sort -hr  e.g. 10.2G foo/ 4M bar/  - Nice. As a function: function dush { du -sh "$@" | sort -hr; } – ColinM Mar 2 '12 at 22:38

double star expansion with zsh (which recursively descends the directory tree, not just one level, something similar to $(find ! -type d): grep string **/*.cc  - I could not live without that. – Stéphane Gimenez Jul 31 '11 at 0:40 Display a prompt where the hostname is bold. I tried color prompts for a while, but the color would sometimes look bad depending on the background. Bold works for me for light background, dark background, blue backgrounds, etc. This is in my .bashrc :  bold=$(tput bold)
reset=$(tput sgr0) export PS1="\u@$bold$\h$reset$:\w \$ "

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This is for zsh, not bash, fyi (if you haven't used it, you won't regret trying it out). This is really useful for quickly typing out long paths for scp transfers. It works just like using to complete or list available filenames/directories.

Example

scp webdev@example.com:/home/webdev/domains/example.com/http.public/long<tab>


will complete the path to /home/webdev/domains/example.com/http.public/longdirname.

I'm bad at examples, but that should give you the idea. Try it out, it can really save you fingers from typing.

# SSH Completion
zstyle ':completion:*:scp:*' tag-order \
files users 'hosts:-host hosts:-domain:domain hosts:-ipaddr"IP\ Address *'
zstyle ':completion:*:scp:*' group-order \
files all-files users hosts-domain hosts-host hosts-ipaddr
zstyle ':completion:*:ssh:*' tag-order \
users 'hosts:-host hosts:-domain:domain hosts:-ipaddr"IP\ Address *'
zstyle ':completion:*:ssh:*' group-order \
hosts-domain hosts-host users hosts-ipaddr
zstyle '*' single-ignored show

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Funny, my /bin/bash shell does filename expansion with tab just fine. – David Thornley Aug 13 '10 at 12:53
Bash does filename expansion on remote files over ssh? – André Paramés Dec 16 '10 at 14:13

I have folders named in my home folder as Document, Downloads, Temp, etc with the first letter in uppercase. When I work on the terminal it's annoying to shift press the first key when you are cd'ing into a directory. Just key in the following in your terminal and bash would auto-correct the case for you.

shopt -s nocaseglob

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None of the following 'tricks' is technically challenging or impressive, but they have some impact on the other person. If we can't use our jobs to make our lives happier, then we should think again about some things.

I like alias. My favorite trick is to edit the ~/.bash_aliases on the computer of my gf as she is missing and add a line like:

alias gfname='echo Myname is thinking of you'


or another romantic quotation.

Another "trick" I especially like is:

#!/bin/bash
xaa=123
for ((a=1; a <= xaa; a++))
do
#sleep 1;
mail -s "Happy Birthday $a" address@example.com < mails.txt done exit 0  where 123 is the of the person to whom I would like to wish happy birthday and mails.txt contains the message that I would like to write as the body of the email. Sleep 1; is sometimes necessary as there is a limit on fork(). You could also use command line arguments $1 etc...

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I can't live without

set editing-mode vi
set blink-matching-paren on


in my ~/.inputrc.

Activates them in every readline enabled application. Only activating vi command line editing in the shell works via:

set -o vi


Thus, hitting ESC or CTRL+[ gets you the well known vi-command mode. And you can use powerful vi commands everywhere!

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Use pgrep foo instead of ps aux | grep foo if you want to find how many instances of foo are running and their pids:

e.g. instead of ps aux | grep firefox, use pgrep firefox

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if you prefer full ps aux output: function psg { ps aux | grep "[${1:0:1}]${1:1}" } – ColinM Mar 2 '12 at 22:48
function calc() { echo $* p | dc }  dc is a RPN calculator; this function enables me to type the expression as the command arguments: $ calc 5 3 +
8

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There is a great site for this at: http://www.commandlinefu.com/commands/browse

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I found the following useful when constantly switching between Windows and Unix/Linux:

alias dir="ls -l"
alias copy="cp"
alias del="rm"

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Not really a one-liner but I think it's useful. Convert many files to uppercase, for example file_to_upper *php *c. There are many similar cases like converting to lower, renaming all files by suffix/prefix, etc.

file_to_upper ()
{
for file in "$@" do if [ ! -f "$file" ]; then
echo "File $file does not exist"; else mv -f "$file" "echo "$file" | tr '[a-z]' '[A-Z]'" fi done return 0 }  - Mine favorite is to use the python command to make the temporary http server: python -m SimpleHTTPServer and accessing files from this machine over the lan as: http://192.168.1.70:8000 Another one is to download the tar file in extracted form as: wget -qO - http://192.168.1.70:8000/test.bz2 | tar xjvf - Here the link can be any over the www and bz2 can be either gz, tgz or bz2 itself for that matter. - # Backup your fancy dot files automagically # Modular .bashrc --> .bashrc.d mkdir -p ~/.bashrc.d cat<<'EOF' >> ~/.bashrc echo "" echo -n ".bashrc.d warming up: " for script in ~/.bashrc.d/* ; do if [ -x "$script" ] ; then
echo -n "${script##*/} " . "$script"
fi
done
echo ""
echo ""
echo "  All systems are go."
echo ""
EOF


# Safer rm, compatible with Linux and Mac OS X

rm() {
local src
local final_status=0

for src in "$@"; do # Process only non command-line arguments. if [[ "$src" != -* ]]; then
local trash="$HOME/.Trash" if [ ! -e "$src" ]; then
echo "Safer rm: $src: No such file or directory." final_status=1 fi # Create the trash directory if needed. if [ ! -d "$trash" ]; then
# Assume Mac trash, but it'll work on *nix too.
mkdir -p "$trash" if [ ! -d "$trash" ]; then
echo "Safer rm: Unable to create trash directory $trash" echo "" echo " Nothing moved or deleted. Consider carefully:" echo "" echo " /bin/rm -rf$src"
return 1
fi
fi
local dest="$trash/${src##*/}"

# Find a filename combination which does not already exist.
if [ -e "$dest" ]; then # Try appending ISO datetime. dest="$dest.$(date +%Y-%m-%dT%H-%M-%S)" if [ -e "$dest" ]; then
local n=1
# Try increasing monotony.
while [ -e "$dest.$n" ]; do
n = $[n + 1] done dest="$dest.$n" fi fi echo -n "Safer rm: Trashing$src to $dest ..." /bin/mv "$src" "$dest" echo " done." echo "" echo " To restore: /bin/mv '$dest' '$src'" echo "" echo " To purge: /bin/rm -rf '$dest'"
echo ""
echo ""
fi
done
return $final_status }  # Super hot 'cd' up action # Don't ask why I need 15 levels of cd .. alias ..='cd ..' alias .2='cd ../..' alias ...='.2' alias .3='cd ../../..' alias .4='cd ../../../..' alias .5='cd ../../../../..' alias .6='cd ../../../../../..' alias .7='cd ../../../../../../..' alias .8='cd ../../../../../../../..' alias .9='cd ../../../../../../../../..' alias .10='cd ../../../../../../../../../..' alias .11='cd ../../../../../../../../../../..' alias .12='cd ../../../../../../../../../../../..' alias .13='cd ../../../../../../../../../../../../..' alias .14='cd ../../../../../../../../../../../../../..' alias .15='cd ../../../../../../../../../../../../../../..'  # Readline is your one true god. bind -p | egrep -v '(not|self)' # No existential jokes included.  # Terminal fonts After looking at bazillions of fonts, I use 14 pt Monaco, Anti-aliased with iTerm2. # On Mac (Apps): Try this app that gives key bindings. KeyCue (tm)(r)(c)($) gives context of almost ANY running app by simply holding command.

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get the file name with the most recent timestamp in the current directory:

latest () { ls -lrt | tail -1 | awk '{print \$NF}' } 

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You don't need awk if you change ls -l to ls -1. And remove the -r option and change tail to head: it will be slightly faster and more logical. – Mikel May 13 '11 at 11:08
In fact, I gave a version of this function in What customizations have you done that does this, but also supports a -<number> option to say how many most recent files to display. – Mikel May 13 '11 at 11:15

zsh's auto pushd feature:

setopt autopushd


and together with that:

alias dirs='dirs -v'


So that at any time, I can type dirs and I get the history of where I have been:

0   /var/log
1   /tmp
2   /usr/local/bin
3   ~


and then I can cd back into e.g. /usr/local/bin by typing:

cd ~2

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ReTTY, which allows you to move a running program from one terminal to another. That way, if you have an ncurses program running outside of screen, tmux, or ssh, you can attach it to an ssh session or a networked screen or tmux session by running ReTTY inside the terminal where you want to use the program in question. In other words, it is similar to screen and tmux but with the exceptions that (a) it can only run one program at a time, and (b) it can be run after you start the child process.

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sync;sync;sync;reboot

can be really useful sometimes. Be careful !

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On which unix variant is this different from reboot? And why wouldn't you want to shut your system down properly, or at the very least unmount disks as cleanly as possible? – Gilles Sep 16 '10 at 19:36

My personal favorite is

find . -name <i>filename</i> | xargs grep -in '<i>pattern to search for</i>'


What the above command does is find a file of name x and then searches said file for whatever pattern you are looking for. Incredibly useful if you are looking for a particular bit of code in a file that's somewhere in your subdirectories.

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Easier: use zsh or bash 4 and grep -in 'pattern' **/filename – Gilles Sep 16 '10 at 19:36
... or ... find -iname *filename* -exec grep -in '*pattern to search for*' {} \; – Eric Smith Sep 19 '10 at 15:51
Or with recent enough versions of GNU grep: grep -r --include='filename' 'pattern' . – Gilles Oct 6 '10 at 19:26

I find understanding bash key strokes leads to more efficient shelling, and that a lot of them are straight from emacs clarifies their usage (i.e. that meta-XXX is the big brother version of ctrl-XXX command usually).

The "meta" key is usually the "alt" key, but can also be "esc" key. e.g. meta-f can be got with either alt-f or esc f.

For the alt- key mappings to work, you may have to unset "menu access keys" or its equivalent in the console options. Basically if you press alt-f and get the file menu prompt, turn off the alt-key access menus.

ctrl-a / ctrl-e : move to start / end of line basics you can't do without

ctrl-f, meta-f : forward char/word pressing alt-f jumps you forward "1 word" which on command line is pretty much a command or argument

ctrl-b, meta-b : backwards char/word same as alt-f, but backwards to jump backwards through the command line

ctrl-d, meta-d : delete char/word pressing alt-d will delete (to end of) current word under cursor. much faster then holding delete down for 30 secs. Useful when you're tab completing in the middle of something and want to forward delete to the end of word.

ctrl-k : kill line deletes to the end of line

ctrl-u : undo e.g. typing a password, and you know you've got it wrong somewhere, instead of hitting backspace 20 times, just hit ctrl-u. also clears the current command line.

meta-# : insert comment this is great for keeping your command line you're building up as a comment before running it if you need to do something else first. it will go into your command history but not run.

ctrl-r : reverse search searching backwards through your shell history (repeated ctrl-r for next match)

ctrl-g : abort if you're in middle of ctrl-r and want to just get back to where you were typing, just abort your search with ctrl-g

meta-space / ctrl-x ctrl-x : set mark and jump to mark if you need to quickly jump to a position in your command line, first set the mark, then jump back to it with ctrl-x ctrl-x. Note you may have to use esc-space to get the mark set as alt-space is often bound to bringing down the console menu.

ctrl-] <char> : quick jump to <char> jumps forward to the character typed after the ctrl-] on command line. The big brother Meta-ctrl-] <char> jumps backwards.

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