Commands using echo (1,545)

  • Tweak system files without invoking a root shell

    only for sudo-style systems. Use this construct instead of I/O re-directors ``>'' or ``>>'' because sudo only elevates the commands and *not* the re-directors. ***warning: remember that the `tee` command will clobber file contents unless it is given the ``-a'' argument Also, for extra security, the "left" command is still run unprivileged. Show Sample Output


    4
    echo "Whatever you need" | sudo tee [-a] /etc/system-file.cfg
    asmoore82 · 2009-03-09 01:33:31 7
  • Count to 65535 in binary (for no apparent reason)

    Yes, it's useless.


    4
    a=`printf "%*s" 16`;b=${a//?/{0..1\}}; echo `eval "echo $b"`
    rhythmx · 2009-06-13 06:32:35 5
  • How much RAM is Apache using?

    Display the amount of memory used by all the httpd processes. Great in case you are being Slashdoted!


    4
    ps -o rss -C httpd | tail -n +2 | (sed 's/^/x+=/'; echo x) | bc
    ricardoarguello · 2009-07-31 15:15:08 9
  • Faster find and move using the find and xargs commands. Almost as fast as locate.

    Only tested on Linux Ubunty Hardy. Works when file names have spaces. The "-maxdepth 2" limits the find search to the current directory and the next one deeper in this example. This was faster on my system because find was searching every directory before the current directory without the -maxdepth option. Almost as fast as locate when used as above. Must use double quotes around pattern to handle spaces in file names. -print0 is used in combination with xargs -0. Those are zeros not "O"s. For xargs, -I is used to replace the following "{}" with the incoming file-list items from find. Echo just prints to the command line what is happening with mv. mv needs "{}" again so it knows what you are moving from. Then end with the move destination. Some other versions may only require one "{}" in the move command and not after the -I, however this is what worked for me on Ubuntu 8.04. Some like to use -type f in the find command to limit the type. Show Sample Output


    4
    find . -maxdepth 2 -name "*somepattern" -print0 | xargs -0 -I "{}" echo mv "{}" /destination/path
    jonasrullo · 2009-08-01 01:55:47 7
  • for all who don't have the watch command

    #Usage: watch timeinsecond "command" Show Sample Output


    4
    watch() { while test :; do clear; date=$(date); echo -e "Every "$1"s: $2 \t\t\t\t $date"; $2; sleep $1; done }
    peshay · 2009-08-19 15:29:00 3
  • Happy Days

    This never gets old Show Sample Output


    4
    echo {1..3}" o'clock" ROCK
    JackiesJungle · 2009-09-14 15:39:07 5
  • Change Title of Terminal Window to Verbose Info useful at Login

    I usually have 5 or more ssh connections to various servers, and putting this command in my .bash_profile file makes my putty window or x terminal window title change to this easily recognizable and descriptive text. Includes the username, group, server hostname, where I am connecting from (for SSH tunneling), which device pts, current server load, and how many processes are running. You can also use this for your PROMPT_COMMAND variable, which updates the window title to the current values each time you exec a command. I prefix running this in my .bash_profile with [[ ! -z "$SSH_TTY" ]] && which makes sure it only does this when connecting via SSH with a TTY. Here's some rougher examples from http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html # If set, the value is executed as a command prior to issuing each primary prompt. #H=$((hostname || uname -n) 2>/dev/null | sed 1q);W=$(whoami) #export PROMPT_COMMAND='echo -ne "\033]0;${W}@${H}:${PWD/#$HOME/~} ${SSH_TTY/\/dev\//} [`uptime|sed -e "s/.*: \([^,]*\).*/\1/" -e "s/ //g"`]\007"' #PROMPT_COMMAND='echo -ne "\033]0;`id -un`:`id -gn`@`hostname||uname -n 2>/dev/null|sed 1q` `command who -m|sed -e "s%^.* \(pts/[0-9]*\).*(\(.*\))%[\1] (\2)%g"` [`uptime|sed -e "s/.*: \([^,]*\).*/\1/" -e "s/ //g"` / `command ps aux|wc -l`]\007"' #[[ -z "$SSH_TTY" ]] || export PROMPT_COMMAND #[[ -z "$SSH_TTY" ]] && [[ -f /dev/stdout ]] && SSH_TTY=/dev/stdout And here's a simple function example for setting the title: function set_window_title(){ echo -e "\033]0; ${1:-$USER@$HOST - $SHLVL} \007"; } Show Sample Output


    4
    echo -ne "\033]0;`id -un`:`id -gn`@`hostname||uname -n|sed 1q` `who -m|sed -e "s%^.* \(pts/[0-9]*\).*(\(.*\))%[\1] (\2)%g"` [`uptime|sed -e "s/.*: \([^,]*\).*/\1/" -e "s/ //g"` / `ps aux|wc -l`]\007"
    AskApache · 2009-09-19 06:57:53 4
  • Create subdirectory and move files into it

    With this form you dont need to cut out target directory using grep/sed/etc.


    4
    (ls; mkdir subdir; echo subdir) | xargs mv
    mechmind · 2009-11-08 11:40:55 13
  • Convert decimal numbers to binary

    Convert some decimal numbers to binary numbers. You could also build a general base-converter: function convBase { echo "ibase=$1; obase=$2; $3" | bc; } then you could write function decToBun { convBase 10 2 $1; } Show Sample Output


    4
    function decToBin { echo "ibase=10; obase=2; $1" | bc; }
    woxidu · 2009-11-24 22:57:58 3
  • How many days until the end of the year


    4
    echo "There are $(($(date +%j -d"Dec 31, $(date +%Y)")-$(date +%j))) left in year $(date +%Y)."
    unixhome · 2010-02-06 00:15:40 13
  • Pipe text from shell to windows cut and paste buffer using PuTTY and XMing.

    Set up X forwarding in PuTTY, with X display location set to :0.0 Launch PuTTY ssh session. Launch Xming. Make sure that display is set to :0.0 (this is default). echo "I'm going to paste this into WINDERS XP" | xsel -i will insert the string into the windows cut and paste buffer. Thanks to Dennis Williamson at stackoverflow.com for sharing...


    4
    echo "I'm going to paste this into WINDERS XP" | xsel -i
    bartonski · 2010-02-08 00:23:43 9
  • Determine whether a CPU has 64 bit capability or not

    Check if you have 64bit by looking for "lm" in cpuinfo. lm stands for "long mem". This can also be used without being root.


    4
    if cat /proc/cpuinfo | grep " lm " &> /dev/null; then echo "Got 64bit" ; fi
    xeor · 2010-04-10 15:31:58 6
  • Hex math with bc

    To do hex to binary: echo 'ibase=16; obase=2; 16*16' | bc # prints: 111100100 To do 16*16 from decimal to hex: echo 'ibase=10; obase=16; 16*16' | bc # prints: 100 You get the idea... Alternatively, run bc in interactive mode (see man page) Show Sample Output


    4
    echo 'obase=16; C+F' | bc
    rkulla · 2010-04-14 20:35:31 7
  • convert ascii string to hex

    just a bit simpler


    4
    echo $ascii | perl -ne 'printf "%x", ord for split //'
    linuxrawkstar · 2010-04-19 11:57:08 4
  • Simplest port scanner

    Very handy way to perform a host scan if you don't have nmap,ncat,nc ...or other tools installed locally. When executing a command on a /dev/tcp/$host/$port pseudo-device file, Bash opens a TCP connection to the associated socket and UDP connection when using /dev/udp/$host/$port.A simlpe way to get servers banner is to run this command "cat < /dev/tcp/localhost/25" , here you will get mail server's banner. NOTE: Bash, as packaged for Debian, does not support using the /dev/tcp and /dev/udp pseudo-device it's not enabled by default Because bash in Debian is compiled with ?disable-net-redirections. Show Sample Output


    4
    for p in {1..1023}; do(echo >/dev/tcp/localhost/$p) >/dev/null 2>&1 && echo "$p open"; done
    benyounes · 2010-04-26 18:09:22 41
  • Search shoutcast web radio by keyword

    Searches for web radio by submitted keyword and returns the station name and the link for listing . May be enhanced to read user's selection and submit it to mplayer. Show Sample Output


    4
    echo "Keyword?";read keyword;query="http://www.shoutcast.com/sbin/newxml.phtml?search="$keyword"";curl -s $query |awk -F '"' 'NR <= 4 {next}NR>15{exit}{sub(/SHOUTcast.com/,"http://yp.shoutcast.com/sbin/tunein-station.pls?id="$6)}{print i++" )"$2}'
    benyounes · 2010-05-03 00:44:10 8
  • Check if a web page has changed last time checked.

    Checks if a web page has changed. Put it into cron to check periodically. Change http://www.page.de/test.html and mail@mail.de for your needs.


    4
    HTMLTEXT=$( curl -s http://www.page.de/test.html > /tmp/new.html ; diff /tmp/new.html /tmp/old.html ); if [ "x$HTMLTEXT" != x ] ; then echo $HTMLTEXT | mail -s "Page has changed." mail@mail.de ; fi ; mv /tmp/new.html /tmp/old.html
    Emzy · 2010-07-04 21:45:37 5
  • delay execution of a command that needs lots of memory and CPU time until the resources are available

    [ 2000 -ge "$(free -m | awk '/buffers.cache:/ {print $4}')" ] returns true if less than 2000 MB of RAM are available, so adjust this number to your needs. [ $(echo "$(uptime | awk '{print $10}' | sed -e 's/,$//' -e 's/,/./') >= $(grep -c ^processor /proc/cpuinfo)" | bc) -eq 1 ] returns true if the current machine load is at least equal to the number of CPUs. If either of the tests returns true we wait 10 seconds and check again. If both tests return false, i.e. 2GB are available and machine load falls below number of CPUs, we start our command and save it's output in a text file. The ( ( ... ) & ) construct lets the command run in background even if we log out. See http://www.commandlinefu.com/commands/view/3115/ .


    4
    ( ( while [ 2000 -ge "$(free -m | awk '/buffers.cache:/ {print $4}')" ] || [ $(echo "$(uptime | awk '{print $10}' | sed -e 's/,$//' -e 's/,/./') >= $(grep -c ^processor /proc/cpuinfo)" | bc) -eq 1 ]; do sleep 10; done; my-command > output.txt ) & )
    michelsberg · 2010-07-13 09:12:11 3
  • I finally found out how to use notify-send with at or cron

    The simplest way to do it. Works for me, at least. (Why are the variables being set?)


    4
    echo notify-send test | at now+1minute
    polar · 2010-08-08 03:11:11 7
  • display a smiling smiley if the command succeeded and a sad smiley if the command failed

    you could save the code between if and fi to a shell script named smiley.sh with the first argument as and then do a smiley.sh to see if the command succeeded. a bit needless but who cares ;) Show Sample Output


    4
    <commmand>; if [[ "$?" = 0 ]]; then echo ':)'; else echo ':('; fi
    potatoface · 2010-08-23 20:35:31 13
  • Boot another OS at next startup


    4
    echo "savedefault --default=2 --once" | grub --batch; sudo reboot
    binfalse · 2010-08-31 22:40:19 4
  • Binary clock

    Like 7171, but fixed typo, uses fewer variables, and even more cryptic! Show Sample Output


    4
    read -a A<<<".*.**..*....*** 8 9 5 10 6 0 2 11 7 4";for C in `date +"%H%M"|fold -w1`;do echo "${A:${A[C+1]}:4}";done
    __ · 2010-12-02 22:04:49 4
  • 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.


    4
    echo <percentage> > /proc/acpi/video/VGA/LCD/brightness
    renan2112 · 2010-12-29 13:51:45 10
  • Console clock -- within screen

    Configures screen to always display the clock in the last line (has to be configured only once). After that you not only have got the possibility to detach sessions and run them in background, but also have got a nice clock permanently on your screen.


    4
    echo 'hardstatus alwayslastline " %d-%m-%y %c:%s | %w"' >> $HOME/.screenrc; screen
    olorin · 2011-02-16 08:04:56 4
  • Email yourself a short note

    I created this so I could send myself an email alert when a long-running job was finished, e.g., my_long_job.exe ; quickemail my_long_job.exe has finished


    4
    quickemail() { echo "$*" | mail -s "$*" email@email.com; }
    dbh · 2011-02-22 20:33:18 3
  • ‹ First  < 8 9 10 11 12 >  Last ›

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

Share Your Commands

Check These Out

Print github url for the current url
Works for repos cloned via ssh or https.

Adequately order the page numbers to print a booklet
Useful if you don't have at hand the ability to automatically create a booklet, but still want to. F is the number of pages to print. It *must* be a multiple of 4; append extra blank pages if needed. In evince, these are the steps to print it, adapted from https://help.gnome.org/users/evince/stable/duplex-npage.html.en : 1) Click File ▸ Print. 2) Choose the General tab. Under Range, choose Pages. Type the numbers of the pages in this order (this is what this one-liner does for you): n, 1, 2, n-1, n-2, 3, 4, n-3, n-4, 5, 6, n-5, n-6, 7, 8, n-7, n-8, 9, 10, n-9, n-10, 11, 12, n-11... ...until you have typed n-number of pages. 3) Choose the Page Setup tab. - Assuming a duplex printer: Under Layout, in the Two-side menu, select Short Edge (Flip). - If you can only print on one side, you have to print twice, one for the odd pages and one for the even pages. In the Pages per side option, select 2. In the Page ordering menu, select Left to right. 4) Click Print.

Protect against buffer overflow
This command solve the problem ping: sendmsg: No buffer space available to.

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"

Test your total disk IO capacity, regardless of caching, to find out how fast the TRUE speed of your disks are
Depending on the speed of you system, amount of RAM, and amount of free disk space, you can find out practically how fast your disks really are. When it completes, take the number of MB copied, and divide by the line showing the "real" number of seconds. In the sample output, the cached value shows a write speed of 178MB/s, which is unrealistic, while the calculated value using the output and the number of seconds shows it to be more like 35MB/s, which is feasible.

locate bin, src, and man file for a command

Vi - Matching Braces, Brackets, or Parentheses
This is a simple command for jumping to the matching brace, square bracket, or parentheses. For example, it can take you from the beginning of a function to the end with one key stroke. To delete everything between the pairs of {}, [], or (), issue the command: $ d% To replace text between pairs of braces, brackets, or parentheses, issue the command: $ c% You can also use this command to find out if an opening brace has been properly closed.

list block devices
Shows all block devices in a tree with descruptions of what they are.

Check if a package is installed. If it is, the version number will be shown.
If the first two letters are "ii", then the package is installed. You can also use wildcards. For example, . $ dpkg -l openoffice* . Note that dpkg will usually not report packages which are available but uninstalled. If you want to see both which versions are installed and which versions are available, use this command instead: . $ apt-cache policy python

run remote linux desktop
First of all you need to run this command. X :12.0 vt12 2>&1 >/dev/null & This command will open a X session on 12th console. And it will show you blank screen. Now press Alt + Ctrl + F7. You will get your original screen. Now run given command "xterm -display :12.0 -e ssh -X user@remotesystem &". After this press Alt + Ctrl + F12. You will get a screen which will ask you for password for remote linux system. And after it you are done. You can open any window based application of remote system on your desktop. Press Alt + Ctrl + F7 for getting original screen.

Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for: