Commands tagged output (15)


  • 58
    strace -ff -e trace=write -e write=1,2 -p SOME_PID
    oernii2 · 2010-04-20 08:55:54 2
  • Run the alias command, then issue ps aux | head and resize your terminal window (putty/console/hyperterm/xterm/etc) then issue the same command and you'll understand. ${LINES:-`tput lines 2>/dev/null||echo -n 12`} Insructs the shell that if LINES is not set or null to use the output from `tput lines` ( ncurses based terminal access ) to get the number of lines in your terminal. But furthermore, in case that doesn't work either, it will default to using the deafault of 12 (-2 = 10). The default for HEAD is to output the first 10 lines, this alias changes the default to output the first x lines instead, where x is the number of lines currently displayed on your terminal - 2. The -2 is there so that the top line displayed is the command you ran that used HEAD, ie the prompt. Depending on whether your PS1 and/or PROMPT_COMMAND output more than 1 line (mine is 3) you will want to increase from -2. So with my prompt being the following, I need -7, or - 5 if I only want to display the commandline at the top. ( http://www.askapache.com/linux-unix/bash-power-prompt.html ) 275MB/748MB [7995:7993 - 0:186] 06:26:49 Thu Apr 08 [[email protected]:/dev/pts/0 +1] ~ In most shells the LINES variable is created automatically at login and updated when the terminal is resized (28 linux, 23/20 others for SIGWINCH) to contain the number of vertical lines that can fit in your terminal window. Because the alias doesn't hard-code the current LINES but relys on the $LINES variable, this is a dynamic alias that will always work on a tty device. Show Sample Output


    26
    alias head='head -n $((${LINES:-`tput lines 2>/dev/null||echo -n 12`} - 2))'
    AskApache · 2010-04-08 22:37:06 7
  • similar to the previous command, but with more friendly output (tested on linux)


    10
    strace -ff -e write=1,2 -s 1024 -p PID 2>&1 | grep "^ |" | cut -c11-60 | sed -e 's/ //g' | xxd -r -p
    systemj · 2010-04-23 16:22:17 0
  • This is super fast and an easy way to test your terminal for 256 color support. Unlike alot of info about changing colors in the terminal, this uses the ncurses termcap/terminfo database to determine the escape codes used to generate the colors for a specific TERM. That means you can switch your terminal and then run this to check the real output. tset xterm-256color at any rate that is some super lean code! Here it is in function form to stick in your .bash_profile aa_256 () { ( x=`tput op` y=`printf %$((${COLUMNS}-6))s`; for i in {0..256}; do o=00$i; echo -e ${o:${#o}-3:3} `tput setaf $i;tput setab $i`${y// /=}$x; done ) } From my bash_profile: http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html Show Sample Output


    7
    ( x=`tput op` y=`printf %$((${COLUMNS}-6))s`;for i in {0..256};do o=00$i;echo -e ${o:${#o}-3:3} `tput setaf $i;tput setab $i`${y// /=}$x;done; )
    AskApache · 2010-09-06 10:39:27 2
  • Optionally, you can create a new function to do this with a custom command. Edit $HOME/.bashrc and add: myssh () { ssh $1 | tee sshlog ; } Save it. At command prompt: myssh [email protected] Show Sample Output


    6
    ssh [email protected] | tee logfilename
    bassu · 2009-04-17 19:17:02 2
  • Output of a command as input to many Show Sample Output


    5
    echo 'foo' | tee >(wc -c) >(grep o) >(grep f)
    totti · 2013-01-31 09:54:18 0
  • This command list and sort files by size and in reverse order, the reverse order is very helpful when you have a very long list and wish to have the biggest files at the bottom so you don't have scrool up. The file size info is in human readable output, so ex. 1K..234M...3G Tested with Linux (Red Hat Enterprise Edition)


    4
    ls -S -lhr
    rez0r · 2009-04-28 01:28:57 0
  • One of my favorite ways to impress newbies (and old hats) to the power of the shell, is to give them an incredibly colorful and amazing version of the top command that runs once upon login, just like running fortune on login. It's pretty sweet believe me, just add this one-liner to your ~/.bash_profile -- and of course you can set the height to be anything, from 1 line to 1000! G=$(stty -g);stty rows $((${LINES:-50}/2));top -n1; stty $G;unset G Doesn't take more than the below toprc file I've added below, and you get all 4 top windows showing output at the same time.. each with a different color scheme, and each showing different info. Each window would normally take up 1/4th of your screen when run like that - TOP is designed as a full screen program. But here's where you might learn something new today on this great site.. By using the stty command to change the terminals internal understanding of the size of your terminal window, you force top to also think that way as well. # save the correct settings to G var. G=$(stty -g) # change the number of rows to half the actual amount, or 50 otherwise stty rows $((${LINES:-50}/2)) # run top non-interactively for 1 second, the output stays on the screen (half at least) top -n1 # reset the terminal back to the correct values, and clean up after yourself stty $G;unset G This trick from my [ http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html bash_profile ], though the online version will be updated soon. Just think what else you could run like this! Note 1: I had to edit the toprc file out due to this site can't handle that (uploads/including code). So you can grab it from [ http://www.askapache.com/linux-unix/bash-power-prompt.html my site ] Note 2: I had to come back and edit again because the links weren't being correctly parsed Show Sample Output


    3
    G=$(stty -g);stty rows $((${LINES:-50}/2));top -n1; stty $G;unset G
    AskApache · 2010-04-22 18:52:49 1
  • Useful to recover a output(stdout and stderr) "disown"ed or "nohup"ep process of other instance of ssh. With the others options the stdout / stderr is intercepted, but only the first n chars. This way we can recover ALL text of stdout or stderr Show Sample Output


    3
    strace -e write=1,2 -p $PID 2>&1 | sed -un "/^ |/p" | sed -ue "s/^.\{9\}\(.\{50\}\).\+/\1/g" -e 's/ //g' | xxd -r -p
    glaudiston · 2010-10-06 19:37:39 1
  • Great way to quickly grasp if a locally cloned repository originates from e.g. github or elsewhere. Show Sample Output


    1
    git config --local --get remote.origin.url
    hced · 2011-10-03 09:29:34 0
  • Useful to know, especially if you are dealing with output configurations in block size. Tested on 'Red Hat'.


    0
    /sbin/dumpe2fs /dev/hda2 | grep 'Block size'
    rez0r · 2009-05-15 22:23:21 0
  • This is similar to using `!!` or In bash 4.1 it seems you can bind directly to a shell command, but I'm not running that version. Show Sample Output


    0
    bind '"\C-h": "\`fc\ \-s\`"'
    rthemocap · 2010-08-16 17:58:16 0
  • Basically, \033[ is a semi-portable unix escape character. It should work in linux, osx, bsd, etc. The first option is 38. This tells whatever is interpreting this (and this is merely convention) that a special color sequence follows. The next option is 5 which says that the next option will specify a color ? {0..256} of course. These options, as you can see, are separated by a single `;` and the entire escape sequence is followed by a mandatory `m`. The second escape sequence (following "COLOR") is simply to clear all terminal attributes (for our purposes, it clears color). This for loop is helpful for testing all 256 colors in a 256 console (note: this will not work in a standard Linux tty console) or to see which number corresponds to which color so that perhaps you can use it! Show Sample Output


    0
    for i in {0..256}; do echo -e "${i} \033[38;05;${i}m COLOR \033[0m"; done
    Benharper · 2015-12-17 23:49:42 0
  • Adds the stdout (standard output) to the beginning of logfile.txt. Change "command" to whatever command you like, such as 'ls' or 'date', etc. It does this by adding the output to a temporary file, then adding the previous contents of logfile.txt to the temp file, then copying the new contents back to the logfile.txt and removing the temp file.


    -2
    command > tmp && cat logfile.txt >> tmp && tmp > logfile.txt && rm tmp
    akoumjian · 2009-04-05 22:00:32 7

  • -2
    sed -n '/jan\|Jan\|JAN\|JAn\|jAn\|jAN\|jaN/p' data.txt > jan-only-data.txt
    Kali_Root · 2013-11-15 20:23:53 2

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

securely erase unused blocks in a partition
This command securely erases all the unused blocks on a partition. The unused blocks are the "free space" on the partition. Some of these blocks will contain data from previously deleted files. You might want to use this if you are given access to an old computer and you do not know its provenance. The command could be used while booted from a LiveCD to clear freespace space on old HD. On modern Linux LiveCDs, the "ntfs-3g" system provides ReadWrite access to NTFS partitions thus enabling this method to also be used on Wind'ohs drives. NB depending on the size of the partition, this command could take a while to complete.

Show crontabs for all users
added echo "### Crontabs for $user ####"; to make clear whose crontab is listed.

Delete DOS Characters via VIM (^M)
And in case you want to migrate back to, err.. MS-DOS: ":set ff=dos" does the opposite.

Find where a kind of file is stored
In this case searches for where .desktop files are stored. The resulted is a sorted list of the top directories containing such files.

Upgrade all perl modules via CPAN

Install pip with Proxy
Installs pip packages defining a proxy

.inputrc keybinding to wrap current line in inotifytools for instant compile/test-as-you-save-loop
Assuming you've written all of make -j hfst-tokenize && echo doavtter gr?dakursa|./hfst-tokenize --gtd tokeniser-gramcheck-gt-desc.pmhfst and want that to execute every time you :w in vim (or C-xC-s in Emacs), just hit and it'll turn into $ while true; do ( make -j hfst-tokenize && e doavtter gr?dakursa|./hfst-tokenize --gtd tokeniser-gramcheck-gt-desc.pmhfst ); inotifywait -q -e modify -e close_write *; done with the cursor right before the ')'. Hit enter, and it'll run on each save. Requires the package inotify-tools installed.

cpu info

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

recursive search and replace old with new string, inside files
This command find all files in the current dir and subdirs, and replace all occurances of "oldstring" in every file with "newstring".


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: