Commands tagged bash (804)

  • This function displays the latest comic from xkcd.com. One of the best things about xkcd is the title text when you hover over the comic, so this function also displays that after you close the comic. To get a random xkcd comic, I also use the following: xkcdrandom(){ wget -qO- dynamic.xkcd.com/comic/random|tee >(feh $(grep -Po '(?<=")http://imgs[^/]+/comics/[^"]+\.\w{3}'))|grep -Po '(?<=(\w{3})" title=").*(?=" alt)';}


    24
    xkcd(){ wget -qO- http://xkcd.com/|tee >(feh $(grep -Po '(?<=")http://imgs[^/]+/comics/[^"]+\.\w{3}'))|grep -Po '(?<=(\w{3})" title=").*(?=" alt)';}
    eightmillion · 2009-11-27 09:11:47 11

  • 24
    <ESC> .
    wincus · 2010-01-22 14:27:44 6
  • This command creates and burns a gapless audio CD with 99 tracks. Each track is a 30 second sine wave, the first is 1 Hz, the second 2 Hz, and so on, up to 99 Hz. This is useful for testing audio systems (how low can your bass go?) and for creating the constant vibrations needed to make non-Newtonian fluids (like cornstarch and water) crawl around. Note, this temporarily creates 500MB of .cdda files in the current directory. If you don't use the "rm" at the end of the command, you can burn more disks using cdrdao write cdrdao.toc Prerequisites: a blank CD-R in /dev/cdrw, sox (http://sox.sourceforge.net/), and cdrdao (http://cdrdao.sourceforge.net/). I'm also assuming a recent version of bash for the brace expansion (which just looks nicer than using seq(1), but isn't necessary). Show Sample Output


    23
    (echo CD_DA; for f in {01..99}; do echo "$f Hz">&2; sox -nt cdda -r44100 -c2 $f.cdda synth 30 sine $f; echo TRACK AUDIO; echo FILE \"$f.cdda\" 0; done) > cdrdao.toc && cdrdao write cdrdao.toc && rm ??.cdda cdrdao.toc
    hackerb9 · 2009-11-17 06:23:42 3
  • If you have some drive imaging to do, you can boot into any liveCD and use a commodity machine. The drives will be written in parallel. To improve efficiency, specify a larger block size in dd: dd if=/dev/sda bs=64k | tee >(dd of=/dev/sdb bs=64k) | dd of=/dev/sdc bs=64k To image more drives , insert them as additional arguments to tee: dd if=/dev/sda | tee >(dd of=/dev/sdb) >(dd of=/dev/sdc) >(dd of=/dev/sdd) | dd of=/dev/sde


    23
    dd if=/dev/sda | tee >(dd of=/dev/sdb) | dd of=/dev/sdc
    nerd65536 · 2009-12-11 17:34:38 2
  • This makes an alias for a command named 'busy'. The 'busy' command opens a random file in /usr/include to a random line with vim. Drop this in your .bash_aliases and make sure that file is initialized in your .bashrc.


    23
    alias busy='my_file=$(find /usr/include -type f | sort -R | head -n 1); my_len=$(wc -l $my_file | awk "{print $1}"); let "r = $RANDOM % $my_len" 2>/dev/null; vim +$r $my_file'
    busybee · 2010-03-09 21:48:41 8
  • If you have used bash for any scripting, you've used the date command alot. It's perfect for using as a way to create filename's dynamically within aliases,functions, and commands like below.. This is actually an update to my first alias, since a few commenters (below) had good observations on what was wrong with my first command. # creating a date-based ssh-key for askapache.github.com ssh-keygen -f ~/.ssh/`date +git-$USER@$HOSTNAME-%m-%d-%g` -C 'webmaster@askapache.com' # /home/gpl/.ssh/git-gplnet@askapache.github.com-04-22-10 # create a tar+gzip backup of the current directory tar -czf $(date +$HOME/.backups/%m-%d-%g-%R-`sed -u 's/\//#/g' <<< $PWD`.tgz) . # tar -czf /home/gpl/.backups/04-22-10-01:13-#home#gpl#.rr#src.tgz . I personally find myself having to reference date --help quite a bit as a result. So this nice alias saves me a lot of time. This is one bdash mofo. Works in sh and bash (posix), but will likely need to be changed for other shells due to the parameter substitution going on.. Just extend the sed command, I prefer sed to pretty much everything anyways.. but it's always preferable to put in the extra effort to go for as much builtin use as you can. Otherwise it's not a top one-liner, it's a lazyboy recliner. Here's the old version: alias dateh='date --help|sed "/^ *%%/,/^ *%Z/!d;s/ \+/ /g"|while read l;do date "+ %${l/% */}_${l/% */}_${l#* }";done|column -s_ -t' This trick from my [ http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html bash_profile ] Show Sample Output


    21
    alias dateh='date --help|sed -n "/^ *%%/,/^ *%Z/p"|while read l;do F=${l/% */}; date +%$F:"|'"'"'${F//%n/ }'"'"'|${l#* }";done|sed "s/\ *|\ */|/g" |column -s "|" -t'
    AskApache · 2010-04-21 01:22:18 5
  • If you should happen to find yourself needing some binary numbers, this is a quickie way of doing it. If you need more digits, just add more "{0..1}" sequences for each digit you need. You can assign them to an array, too, and access them by their decimal equivalent for a quickie binary to decimal conversion (for larger values it's probably better to use another method). Note: this works in bash, ksh and zsh. For zsh, though, you'll need to issue a setopt KSH_ARRAYS to make the array zero-based. binary=({0..1}{0..1}{0..1}{0..1}) echo ${binary[9]} Show Sample Output


    18
    echo {0..1}{0..1}{0..1}{0..1}
    dennisw · 2009-06-23 17:30:20 5
  • This function takes a word or a phrase as arguments and then fetches definitions using Google's "define" syntax. The "nl" and perl portion isn't strictly necessary. It just makes the output a bit more readable, but this also works: define(){ local y="$@";curl -sA"Opera" "http://www.google.com/search?q=define:${y// /+}"|grep -Po '(?<=<li>)[^<]+';} If your version of grep doesn't have perl compatible regex support, then you can use this version: define(){ local y="$@";curl -sA"Opera" "http://www.google.com/search?q=define:${y// /+}"|grep -Eo '<li>[^<]+'|sed 's/<li>//g'|nl|perl -MHTML::Entities -pe 'decode_entities($_)' 2>/dev/null;} Show Sample Output


    18
    define(){ local y="$@";curl -sA"Opera" "http://www.google.com/search?q=define:${y// /+}"|grep -Po '(?<=<li>)[^<]+'|nl|perl -MHTML::Entities -pe 'decode_entities($_)' 2>/dev/null;}
    eightmillion · 2010-01-29 05:01:11 4
  • Delete a range of line


    18
    sed -i <file> -re '<start>,<end>d'
    Zulu · 2012-02-02 17:59:18 1

  • 17
    env PS4=' ${BASH_SOURCE}:${LINENO}(${FUNCNAME[0]}) ' sh -x /etc/profile
    oernii2 · 2009-10-07 14:44:59 4
  • I've been using linux for almost a decade and only recently discovered that most terminals like putty, xterm, xfree86, vt100, etc., support hundreds of shades of colors, backgrounds and text/terminal effects. This simply prints out a ton of them, the output is pretty amazing. If you use non-x terminals all the time like I do, it can really be helpful to know how to tweak colors and terminal capabilities. Like: echo $'\33[H\33[2J'


    17
    for c in `seq 0 255`;do t=5;[[ $c -lt 108 ]]&&t=0;for i in `seq $t 5`;do echo -e "\e[0;48;$i;${c}m|| $i:$c `seq -s+0 $(($COLUMNS/2))|tr -d '[0-9]'`\e[0m";done;done
    AskApache · 2009-11-03 09:12:13 2
  • Bash can accept '0x' and '0' notation for hexidecimal and octal numbers, so you just have to output the values. Show Sample Output


    17
    echo $((0x1fe)) $((033))
    Mozai · 2011-12-06 02:00:42 1
  • Print out list of all branches with last commit date to the branch, including relative time since commit and color coding. Show Sample Output


    16
    for k in `git branch|perl -pe s/^..//`;do echo -e `git show --pretty=format:"%Cgreen%ci %Cblue%cr%Creset" $k|head -n 1`\\t$k;done|sort -r
    brunost · 2009-06-03 08:25:00 3
  • You can specify a range via '-'. Show Sample Output


    16
    !:1-3
    dbbolton · 2010-06-12 02:51:04 0
  • This version uses Pipes, but is easier for the common user to grasp... instead of using sed or some other more complicated method, it uses the tr command Show Sample Output


    15
    echo $PATH | tr \: \\n
    crk · 2009-09-09 02:10:04 2
  • It happens that sometime you remember that you used a special command short time before and you want to check the command again. WIth this command you can just put the beginning of a command and then bash will look for you and it will print back safely withou executing Show Sample Output


    15
    !ssh:p
    acirulli · 2011-10-13 08:37:58 2
  • Ever needed to test firewalls but didn't have netcat, telnet or even FTP? Enter /dev/tcp, your new best friend. /dev/tcp/(hostname)/(port) is a bash builtin that bash can use to open connections to TCP and UDP ports. This one-liner opens a connection on a port to a server and lets you read and write to it from the terminal. How it works: First, exec sets up a redirect for /dev/tcp/$server/$port to file descriptor 5. Then, as per some excellent feedback from @flatcap, we launch a redirect from file descriptor 5 to STDOUT and send that to the background (which is what causes the PID to be printed when the commands are run), and then redirect STDIN to file descriptor 5 with the second cat. Finally, when the second cat dies (the connection is closed), we clean up the file descriptor with 'exec 5>&-'. It can be used to test FTP, HTTP, NTP, or can connect to netcat listening on a port (makes for a simple chat client!) Replace /tcp/ with /udp/ to use UDP instead.


    15
    exec 5<>/dev/tcp/time.nist.gov/13; cat <&5 & cat >&5; exec 5>&-
    tyzbit · 2015-07-30 21:12:38 9
  • Shorter version. Show Sample Output


    14
    echo "${PATH//:/$'\n'}"
    camspiers · 2009-08-26 23:12:05 4
  • Bash history commands are those that begin with the character ! (eg. the most popular 'sudo !!' Explained here => http://www.commandlinefu.com/commands/view/13). By default bash immediately executes the history command. Setting this shell option will make bash first allow you to verify/edit an history command before executing it. To set this option permanently, put this command in ~/.profile or ~/.bashrc file. To unset this option issue following command. shopt -u histverify Show Sample Output


    14
    shopt -s histverify
    b_t · 2011-10-27 00:33:34 0
  • echo "http%3A%2F%2Fwww.google.com" | sed -e's/%\([0-9A-F][0-9A-F]\)/\\\\\x\1/g' | xargs echo -e http://www.google.com Works under bash on linux. just alter the '-e' option to its corresponding equivalence in your system to execute escape characters correctly.


    13
    sed -e's/%\([0-9A-F][0-9A-F]\)/\\\\\x\1/g' | xargs echo -e
    mohan43u · 2009-05-25 05:37:44 3
  • I've used this a number of times troubleshooting user permissions. Instead of just 'su - user' you can throw another hyphen and stay in the original directory. Show Sample Output


    13
    su -- user
    matthewdavis · 2009-09-28 04:23:43 1
  • Though without infinite time and knowledge of how the site will be designed in the future this may stop working, it still will serve as a simple straight forward starting point. This uses the observation that the only item marked as strong on the page is the single logical line that includes the italicized fact. If future revisions of the page show failure, or intermittent failure, one may simply alter the above to read. wget randomfunfacts.com -O - 2>/dev/null | tee lastfact | grep \<strong\> | sed "s;^.*<i>\(.*\)</i>.*$;\1;" The file lastfact, can then be examined whenever the command fails.


    13
    wget randomfunfacts.com -O - 2>/dev/null | grep \<strong\> | sed "s;^.*<i>\(.*\)</i>.*$;\1;"
    tali713 · 2010-03-30 23:49:30 1

  • 13
    compgen -A function
    patrick2000 · 2010-04-30 14:27:16 0

  • 12
    <ALT> .
    new_user · 2010-01-22 15:06:26 2

  • 12
    <ctrl+z> bg
    lucafaus · 2010-10-26 18:07:54 0
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sort list of email addresses by domain.tld
email random list can be created here: https://www.randomlists.com/email-addresses

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Generate hash( of some types) from string
No need to install yet another program when openssl is already installed. :-)

search office documents for credit card numbers and social security number SSN docx xlsx
# CC with SSN dash ( low false positive only match ###-##-#### not any 8digi number ) $ find . -iname "*.???x" -type f -exec unzip -p '{}' '*' \; | sed -e 's/]\{1,\}>/ /g; s/[^[:print:]]\{1,\}/ /g' | egrep "\b4[0-9]{12}(?:[0-9]{3})?\b|\b5[1-5][0-9]{14}\b|\b6011[0-9]{14}\b|\b3(?:0[0-5]\b|\b[68][0-9])[0-9]{11}\b|\b3[47][0-9]{13}\b|\b[0-9]{3}-[0-9]{2}-[0-9]{4}\b" $ rmccurdyDOTcom

Find broken symlinks and delete them
This command is adapted from http://otomaton.wordpress.com/2012/12/26/find-broken-symbolic-links/ Solutions with $ find -L don't work when the link is a loop, an error message is printed.

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Set laptop display brightness
Run as root. Path may vary depending on laptop model and video card (this was tested on an Acer laptop with ATI HD3200 video). $ cat /proc/acpi/video/VGA/LCD/brightness to discover the possible values for your display.

Go up multiple levels of directories quickly and easily.
Change to your taste. Much quicker than having to add 'cd' every time. Add it to your .bashrc or .bash_profile.

Save a file you edited in vim without the needed permissions - (Open)solaris version with RBAC

Mount a partition from within a complete disk dump
Suppose you made a backup of your hard disk with dd: dd if=/dev/sda of=/mnt/disk/backup.img This command enables you to mount a partition from inside this image, so you can access your files directly. Substitute PARTITION=1 with the number of the partition you want to mount (returned from sfdisk -d yourfile.img).


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