All commands (14,187)

  • make password randomly, default 8 char


    -1
    genpass() { local h x y;h=${1:-8};x=( {a..z} {A..Z} {0..9} );y=$(echo ${x[@]} | tr ' ' '\n' | shuf -n$h | xargs);echo -e "${y// /}"; }
    twfcc · 2009-10-24 04:05:42 4
  • Use multiple patterns with grep -v. So you can print all lines in a file except those containing the multiple patterns you specify.


    16
    grep 'test' somefile | grep -vE '(error|critical|warning)'
    zlemini · 2009-10-23 23:21:36 12
  • Alternative to the ping check if your firewall blocks ping. Uses curl to get the landing page silently, or fail with an error code. You can probably do this with wget as well. Show Sample Output


    2
    curl -fs brandx.jp.sme 2&>1 > /dev/null || echo brandx.jp.sme ping failed | mail -ne -s'Server unavailable' joker@jp.co.uk
    mccalni · 2009-10-23 14:29:06 4
  • Strip my code to: wmctrl -o 0,0 # autorotates to the first face. In fact [0-1279],0 wmctrl - 1280,0 # goes to the second face wmctrl -o 2560,0 # goes to the third face, and so on. # Use multiples of the horizontal display resolution. My example work for 1280x800 display, been 1280 the number of interest. Tweak the number, try a biiiig one and see your cube spinning... I put a complex example to show how fun things can be, even for my ademco and paradox alarm central network advisor interface xpto etc. It rotates two faces, print the alarm message, and goes back tho where it was. Tested on BIGLINUX 4.2, equivalent to ubuntu LTS hardy. Do not forget to activate 3D efects ( compiz cube ) Show Sample Output


    5
    wmctrl -o 2560,0 ;sleep 2 ; echo "FIRE 001" | osd_cat -o 470 -s 8 -c red -d 10 -f -*-bitstream\ vera\ sans-*-*-*--250-*-*-*-*-*-*-* ; sleep 1; wmctrl -o 0,0
    m33600 · 2009-10-23 10:00:51 17
  • already described on the other two versions, this one uses ascii characters on game style to display elapsed time. Show Sample Output


    0
    export I=$(date +%s); watch -t -n 1 'T=$(date +%s);E=$(($T-$I));hours=$((E / 3600)) ; seconds=$((E % 3600)) ; minutes=$((seconds / 60)) ; seconds=$((seconds % 60)) ; echo $(printf "%02d:%02d:%02d" $hours $minutes $seconds) | toilet -f shadow'
    m33600 · 2009-10-23 07:56:30 10
  • Variation of the theme, this one blinks in low profile on top level of X, ie, it is visible, indeed small. Try changing fonts and sizes of osd_cat


    0
    export I=$(date +%s); watch -t -n 1 'T=$(date +%s);E=$(($T-$I));hours=$((E / 3600)) ; seconds=$((E % 3600)) ; minutes=$((seconds / 60)) ; seconds=$((seconds % 60)) ; echo $(printf "%02d:%02d:%02d" $hours $minutes $seconds) | osd_cat -o 20 -d 1 -p bottom'
    m33600 · 2009-10-23 07:47:11 3
  • Works on real time clock, unix time based, decrementing the actual time from initial time saved in an environment variable exported to child process inside watch Shows elapsed time from start of script in hh:mm:ss format Non afected by system slow down due to the use of date.


    3
    export I=$(date +%s); watch -t -n 1 'T=$(date +%s);E=$(($T-$I));hours=$((E / 3600)) ; seconds=$((E % 3600)) ; minutes=$((seconds / 60)) ; seconds=$((seconds % 60)) ; echo $(printf "%02d:%02d:%02d" $hours $minutes $seconds)'
    m33600 · 2009-10-23 07:31:44 8
  • simple function , floating point number is supported.


    12
    calc(){ awk "BEGIN{ print $* }" ;}
    twfcc · 2009-10-23 06:03:07 52
  • My firefox overheats my cpu, sometimes above 90 degrees Celsius ( hence the name? ) To keep an eye on temperature, I put this command inside KAlarm ( a kind of cron) to be repeated every minute, for 5 seconds, color red ( default for osd_cat). Its pretty, ultra small, displays a micro 2 lines text on every desktop and over everything and do not steal focus or interrupt any task. I get the information passively, in the low profile bottom of the screen. Of course you can use it inside a terminal. Just do it: watch -n 60 'acpi -t | osd_cat -p bottom'


    2
    acpi -t | osd_cat -p bottom
    m33600 · 2009-10-23 05:22:01 3
  • Usefull as a light blink to remember events, mails, intrusions, etc... yet another output Since nobody ever uses the scroll lock function... Usefull to interface a linux system with some hardware, for example, opto interfacing the keyboard led to a relay to remotely reset, etc. ( a simple LDR glued over the LED will do the trick ) xset led 3 turns on the third led, ie, Scroll lock xset -led 3 turns it off xset led 1 turns on Numerical Lock led ( doesn t work on all computer ) xset led 2 turns on Caps Lock led ( idem ) Using it as a reset watchdog, the relay expected light pulses. Shall the computer hangs, the relay releases and reset the machine ( discharge of a capacitor ) ;-)


    5
    xset led 3
    m33600 · 2009-10-23 00:25:56 15
  • If you omit the function name, the command will display all definitions Show Sample Output


    5
    declare -f [ function_name ]
    haivu · 2009-10-22 17:52:47 6
  • If you issue the "set" command, you'll see a list of variables and functions. This command displays just those functions' names. Show Sample Output


    1
    set | fgrep " ()"
    haivu · 2009-10-22 17:48:54 6
  • Handled all within awk. Takes the value from $PWD and constructs directory structures and runs commands against them. The gsub() call is not necessary, but added for better visibility. If a variable DIR is given on the awk command-line, then that directory is used instead: awk -vDIR=$HOME/.ssh 'BEGIN{dir=DIR?...}' Show Sample Output


    -1
    awk 'BEGIN{dir=DIR?DIR:ENVIRON["PWD"];l=split(dir,parts,"/");last="";for(i=1;i<l+1;i++){d=last"/"parts[i];gsub("//","/",d);system("ls -ld \""d"\"");last=d}}'
    arcege · 2009-10-22 16:28:07 5
  • note the xargs at the end


    5
    shuf -i 1-49 | head -n6 | sort -n| xargs
    ioggstream · 2009-10-22 12:54:08 93
  • Can easily be scripted in order to show permission "tree" from any folder. Can also be formated with column -t { pushd .> /dev/null; cd /; for d in `echo $OLDPWD | sed -e 's/\// /g'`; do cd $d; echo -n "$d "; ls -ld .; done; popd >/dev/null ; } | column -t from http://www.commandlinefu.com/commands/view/3731/using-column-to-format-a-directory-listing Show Sample Output


    0
    pushd .> /dev/null; cd /; for d in `echo $OLDPWD | sed -e 's/\// /g'`; do cd $d; echo -n "$d "; ls -ld .; done; popd >/dev/null
    syladmin · 2009-10-22 12:32:11 3

  • 7
    echo $(shuf -i 1-49 | head -n6 | sort -n)
    twfcc · 2009-10-22 06:48:20 4
  • One character less...


    0
    flip -u <filenames>
    linuxmonkey · 2009-10-21 21:25:43 3
  • atime and mtime timestamps of $FILE2 is changed according to the ones of $FILE1. If $FILE2 doesn't exist is created. Show Sample Output


    2
    touch -r "$FILE1" "$FILE2"
    kobayashison · 2009-10-21 13:53:59 6

  • 0
    shopt -s dotglob
    sharfah · 2009-10-21 13:31:20 3
  • This could be added to .bashrc. Background: Linux usually saves history only on clean exit of shell. If shell ends unclean, history is lost. Also numerous terminals might confuse their history. With this variable set, history is immedeately written, accessible to all other open shells.


    2
    PROMPT_COMMAND="history -a"
    danam · 2009-10-21 12:33:25 4
  • set directly the wallpaper on windowmaker , use this command with display of imagemagick :) Show Sample Output


    1
    wmsetbg -s -u path_to_wallpaper
    eastwind · 2009-10-21 11:23:54 4
  • syntax : mencoder mf://filemask -mf option availble for mf : * w=value : the width of the output, by d?fault : autodetected * h=value : height of the output, by default : autodetected * fps=value : framerate of the output, by default : 25 * type=value : file format type input , avaible: jpeg, png, tga, sgi


    -1
    mencoder mf://image1.jpg,image2.jpg,image3.jpg -mf w=800:h=600:fps=25:type=jpeg -ovc copy -oac copy -o output.avi
    eastwind · 2009-10-21 09:17:22 3
  • syntax : mencoder mf://filemask -mf option availble for mf : * w=value : the width of the output, by d?fault : autodetected * h=value : height of the output, by default : autodetected * fps=value : framerate of the output, by default : 25 * type=value : file format type input , avaible: jpeg, png, tga, sgi Show Sample Output


    0
    mencoder mf://*.jpg -mf w=800:h=600:fps=25:type=jpeg -ovc lavc -lavcopts vcodec=mpeg4 -oac copy -o output.avi
    eastwind · 2009-10-21 09:14:04 3
  • Convert those .mov files that your digital camera makes to .avi Adjust the bitrate (-b) to get the appropriate file size. A larger bitrate produces a larger (higher quality) .avi file and smaller bitrate produces a smaller (lower quality) .avi file. Requires ffmpeg (see man page for details) (tested with canon camera MOV files) Other examples: ffmpeg -i input.mov -sameq -vcodec msmpeg4v2 -acodec pcm_u8 output.avi ffmpeg -i input.mov -b 1024k -vcodec msmpeg4v2 -acodec pcm_u8 output.avi


    1
    ffmpeg -i input.mov -b 4096k -vcodec msmpeg4v2 -acodec pcm_u8 output.avi
    oracular · 2009-10-21 05:44:31 9
  • Just one character longer than the sed version ('FNR==5' versus -n 5p). On my system, without using "exit" or "q", the awk version is over four times faster on a ~900K file using the following timing comparison: testfile="testfile"; for cmd in "awk 'FNR==20'" "sed -n '20p'"; do echo; echo $cmd; eval "$cmd $testfile"; for i in {1..3}; do time for j in {1..100}; do eval "$cmd $testfile" >/dev/null; done; done; done Adding "exit" or "q" made the difference between awk and sed negligible and produced a four-fold improvement over the awk timing without the "exit". For long files, an exit can speed things up: awk 'FNR==5{print;exit}' <file>


    2
    awk 'FNR==5' <file>
    dennisw · 2009-10-20 22:52:41 5
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Search recursively to find a word or phrase in certain file types, such as C code
I have a bash alias for this command line and find it useful for searching C code for error messages. The -H tells grep to print the filename. you can omit the -i to match the case exactly or keep the -i for case-insensitive matching. This find command find all .c and .h files

List your installed Chromium extensions (with url to each page)
Gives you a list for all installed chrome (chromium) extensions with URL to the page of the extension. With this you can easy add a new Bookmark folder called "extensions" add every URL to that folder, so it will be synced and you can access the names from every computer you are logged in. ------------------------------------------------------------------------------------------------------------------ Only tested with chromium, for chrome you maybe have to change the find $PATH.

Convert Squid unixtime logs in human-readable ones
On-the-fly conversion of Unix Time to human-readable in Squid's access.log

Recursively remove all empty directories

Run a command multiple times with different subcommands
it's nice to be able to use the command `ls program.{h,c,cpp}`. This expands to `ls program.h program.c program.cpp`. Note: This is a text expansion, not a shell wildcard type expansion that looks at matching file names to calculate the expansion. More details at http://www.linuxjournal.com/content/bash-brace-expansion I often run multiple commands (like apt-get) one after the other with different subcommands. Just for fun this wraps the whole thing into a single line that uses brace expansion.

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

sed /pat/!d without using sed (no RE; limited to shell patterns aka globbing)
POSIX requires this "string truncating" functionality. might as well use it, at least for very small tasks where invoking sed and using RE is overkill.

Silently ensures that a FS is mounted on the given mount point (checks if it's OK, otherwise unmount, create dir and mount)
In my example, the mount point is /media/mpdr1 and the FS is /dev/sdd1 /mountpoint-path = /media/mpdr1 filesystem=/dev/sdd1 Why this command ? Well, in fact, with some external devices I used to face some issues : during data transfer from the device to the internal drive, some errors occurred and the device was unmounted and remounted again in a different folder. In such situations, the command mountpoint gave a positive result even if the FS wasn't properly mounted, that's why I added the df part. And if the device is not properly mounted, the command tries to unmount, to create the folder (if it exists already it will also work) and finally mount the FS on the given mount point.

List all databases in Postgres and their (byte/human) sizes, ordering by byte size descending
Get a listing of all of your databases in Postgres and their sizes, ordering by the largest size first. Requires that you give the -d parameter a valid database name that you can connect to.

print a python-script (or any other code) with syntax-highlighting and no loss of indentation


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