Commands tagged Linux (266)

  • Have netcat listen on port 8000, point browser to http://localhost:8000/ and you see the information sent. netcat terminates as soon as your browser disconnects. I tested this command on my Fedora box but linuxrawkstar pointed out that he needs to use nc -l -p 8000 instead. This depends on the netcat version you use. The additional '-p' is required by GNU netcat that for example is used by Debian but not by the OpenBSD netcat port used by my Fedora system. Show Sample Output


    2
    nc -l 8000
    penpen · 2009-03-25 23:09:38 6
  • In the above example 'muspi merol' (the output of the first rev command) is sent to stderr and 'lorem ipsum' (the output of the second rev command) is sent to stdout. rev reverse lines of a file or files. This use of tee allows testing if a program correctly handles its input without using files that hold the data. Show Sample Output


    2
    rev <<< 'lorem ipsum' | tee /dev/stderr | rev
    penpen · 2009-03-31 13:12:09 7
  • There was another line that was dependent on having un-named screen sessions. This just wouldn't do. This one works no matter what the name is. A possible improvement would be removing the perl dependence, but that doesn't effect me.


    2
    for i in `screen -ls | perl -ne'if(/^\s+\d+\.([^\s]+)/){print $1, " "}'`; do gnome-terminal -e "screen -x $i"; done
    hank · 2009-04-25 22:39:24 7
  • Shell timeout variables (TMOUT) can be very liberal about what is classified as 'activity', like having an editor open. This command string will terminate the login shell for an user with more than a day's idle time.


    2
    fuser -k `who -u | awk '$6 == "old" { print "/dev/"$2'}`
    lbonanomi · 2009-09-07 03:36:43 5
  • This command gives you the charset of a text file, which would be handy if you have no idea of the encoding. Show Sample Output


    2
    file -i <textfile>
    juvenn · 2009-09-08 01:33:19 4
  • This command will transcode a MythTV recording. The target device is a Google Nexus One mobile phone. My recordings are from a HDHomerun with Over The Air content. Plays back nicely on the N1.


    2
    ffmpeg -i /var/lib/mythtv/pretty/Chuck20100208800PMChuckVersustheMask.mpg -s 800x480 -vcodec mpeg4 -acodec libfaac -ac 2 -ar 16000 -r 13 -ab 32000 -aspect 16:9 Chuck20100208800PMChuckVersustheMask.mp4
    PLA · 2010-02-12 12:11:02 7
  • extension to tali713's random fact generator. It takes the output & sends it to notify-osd. Display time is proportional to the lengh of the fact.


    2
    wget randomfunfacts.com -O - 2>/dev/null | grep \<strong\> | sed "s;^.*<i>\(.*\)</i>.*$;\1;" | while read FUNFACT; do notify-send -t $((1000+300*`echo -n $FUNFACT | wc -w`)) -i gtk-dialog-info "RandomFunFact" "$FUNFACT"; done
    mtron · 2010-04-02 09:43:32 4
  • A little aptitude magic. Note: this will remove images AND headers. If you just want to remove images: aptitude remove ?and(~i~nlinux-im ?not(~n`uname -r`)) I used this in zsh without any problems. I'm not sure how other shells will interpret some of the special characters used in the aptitude search terms. Use -s to simulate.


    2
    aptitude remove ?and(~i~nlinux-(im|he) ?not(~n`uname -r`))
    dbbolton · 2010-06-11 22:57:09 6
  • probably only works if you have one graphics card. used this: http://www.cyberciti.biz/faq/howto-find-linux-vga-video-card-ram/ as reference can be expanded, for example: lspci -v -s `lspci | awk '/VGA/{print $1}'` | sed -n '/Memory.*, prefetchable/s/.*\[size=\([^]]\+\)\]/\1/p' will just get the amount of prefetchable memory compare to: lshw -C display which does not give the size (it does give byte ranges and you could calculate the size from that, but that's a pain) Also uses a command which is not standard on linux; wheras lspci is a core utility provided by most systems Show Sample Output


    2
    lspci -v -s `lspci | awk '/VGA/{print $1}'`
    infinull · 2010-10-26 17:45:14 9
  • Specify the size in bytes using the 'c' option for the -size flag. The + sign reads as "bigger than". Then execute du on the list; sort in reverse mode and show the first 10 occurrences. Show Sample Output


    2
    find /myfs -size +209715200c -exec du -m {} \; |sort -nr |head -10
    arlequin · 2011-07-07 21:12:46 3
  • this will open a new tab in firefox for every line in a file the sleep is removable but i found that if you have a large list of urls 50+, and no sleep, it will try to open all the urls at once and this will cause them all to load a lot slower, also depending on the ram of your system sleep gives you a chance to close the tabs before they overload your ram, removing & >2/dev/null will yield unpredictable results.


    2
    for line in `cat $file`; do firefox -new-tab "$line" & 2>/dev/null; sleep 1; done
    hamsolo474 · 2011-11-12 13:47:24 3
  • Converts a number of bytes provided as input, to a human readable number. Show Sample Output


    2
    human_filesize() { awk -v sum="$1" ' BEGIN {hum[1024^3]="Gb"; hum[1024^2]="Mb"; hum[1024]="Kb"; for (x=1024^3; x>=1024; x/=1024) { if (sum>=x) { printf "%.2f %s\n",sum/x,hum[x]; break; } } if (sum<1024) print "1kb"; } '}
    ArtBIT · 2011-12-02 18:21:20 3
  • "What it actually shows is going to be dependent on the commands you've previously entered. When you do this, bash looks for the last command that you entered that contains the substring "ls", in my case that was "lsof ...". If the command that bash finds is what you're looking for, just hit Enter to execute it. You can also edit the command to suit your current needs before executing it (use the left and right arrow keys to move through it). If you're looking for a different command, hit Ctrl+R again to find a matching command further back in the command history. You can also continue to type a longer substring to refine the search, since searching is incremental. Note that the substring you enter is searched for throughout the command, not just at the beginning of the command." - http://www.linuxjournal.com/content/using-bash-history-more-efficiently Show Sample Output


    2
    <ctrl+r>
    *deleted* · 2012-04-15 16:42:32 5
  • list the top 15 folders by decreasing size in MB Show Sample Output


    2
    du -xB M --max-depth=2 /var | sort -rn | head -n 15
    bouktin · 2013-05-23 10:45:21 6
  • Optionally, pipe the output into http://sed.sourceforge.net/grabbag/scripts/html2iso.sed Or: wget -qO - http://www.asciiartfarts.com/random.cgi | sed -n '//,//p' | sed -n '/ Show Sample Output


    2
    wget -qO - http://www.asciiartfarts.com/random.cgi | sed -n '/<pre>/,/<\/pre>/p' | sed -n '/<table*/,/<\/table>/p' | sed '1d' | sed '$d' | recode html..ascii
    krunktron · 2013-08-17 19:42:47 9

  • 2
    grep -v rootfs /proc/mounts > /etc/mtab
    ohe · 2014-01-21 14:28:12 7
  • To show ipv6 instead, use [[ -6 ]] instead of [[ -4 ]] ip -o -6 a s | awk -F'[ /]+' '$2!~/lo/{print $4}' To show only the IP of a specific interface, in case you get more than one result: ip -o -4 a s eth0 | awk -F'[ /]+' '$2!~/lo/{print $4}' ip -o -4 a s wlan0 | awk -F'[ /]+' '$2!~/lo/{print $4}' Show Sample Output


    2
    ip -o -4 a s | awk -F'[ /]+' '$2!~/lo/{print $4}'
    paulera · 2015-02-13 11:19:31 11

  • 2
    tr '\0' ' ' </proc/21679/cmdline ; echo
    pdxdoughnut · 2015-09-25 22:08:31 16
  • Assumes you've downloaded Toni Corvera's vcs script (http://p.outlyer.net/vcs), have it in your PATH, and have installed the script's dependencies. Generates a video contact sheet of 24 thumbnails and 3 thumbnails per column. The bold font and white-on-black color scheme keeps the text readable at the chosen 70% JPEG compression quality, which keeps the file size at a manageable level. You can go even lower with the quality and get a good looking result.


    2
    vcs -c 3 -H 220 -n 24 -dt -ds -dp -j --anonymous -O bg_heading=black -O bg_sign=black -O fg_heading=white -O fg_heading=white -O fg_sign=white -O fg_title=white -O font_heading=DejaVu-Sans-Bold -O quality=70
    Negate · 2018-06-06 00:49:25 192
  • Uses the shell builtin `declare` with the '-f' flag to output only functions to grep out only the function names. You can use it as an alias or function like so: alias shfunctions="builtin declare -f | command grep --color=never -E '^[a-zA-Z_]+\ \(\)'" shfunctions () { builtin declare -f | command grep --color=never -E '^[a-zA-Z_]+\ \(\)'; } Show Sample Output


    2
    builtin declare -f | command grep --color=never -E '^[a-zA-Z_]+\ \(\)'
    sciro · 2018-07-23 05:24:04 977
  • explanation: grep -- displays process ids -v -- negates the matching, displays all but what is specified in the other options -u -- specifies the user to display, or in this case negate The process loops through all PIDs that are found by pgrep, then orders a forced kill to the processes in numerical order, effectively killing the parent processes first including the shells in use which will force the users to logout. Tested on Slackware Linux 12.2 and Slackware-current


    1
    for i in $(pgrep -v -u root);do kill -9 $i;done
    lostnhell · 2009-03-24 02:54:52 8
  • and, a lot uglier, with sed: ifconfig | sed -n '/inet addr:/s/[^:]\+:\(\S\+\).*/\1/p' Edit: Wanted to be shorter than the perl version. Still think that the perl version is the best..


    1
    ifconfig | awk -F':| +' '/ddr:/{print $4}'
    0x89 · 2009-07-25 22:51:08 4
  • The initial version of this command also outputted extra empty lines, so it went like this: 192.168.166.48 127.0.0.1 This happened on Ubuntu, i haven't tested on anything else. Show Sample Output


    1
    ifconfig | awk '/ddr:[0-9]/ {sub(/addr:/, ""); print $2}'
    danny_b85 · 2009-07-31 09:30:54 3
  • default stack size is 10M. This makes your multithread app filling rapidly your memory. on my PC I was able to create only 300thread with default stack size. Lower the default stack size to the one effectively used by your threads, let you create more. ex. putting 64k I was able to create more than 10.000threads. Obviously ...your thread shouldn't need more than 64k ram!!!


    1
    ulimit -s 64
    ioggstream · 2009-08-06 10:40:25 5
  • you must be in the directory to analyse report all files and links in the currect directory, not recursively. this find command ahs been tested on hp-ux/linux/aix/solaris. Show Sample Output


    1
    find . \( ! -name . -prune \) \( -type f -o -type l \)
    mobidyc · 2009-09-12 15:58:56 11
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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"

Rename files in batch

Download an Entire website with wget

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.

Get AWS temporary credentials ready to export based on a MFA virtual appliance
You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

a short counter
Maybe you know shorter ?

Log colorizer for OSX (ccze alternative)
Download colorizer by @raszi @ http://github.com/raszi/colorize

add all files not under version control to repository
This should handle whitespaces well and will not get confused if your filenames have "?" in them

Sort netflow packet capture
Sort netflow packet capture by unique connections excluding source port.

back ssh from firewalled hosts
host B (you) redirects a modem port (62220) to his local ssh. host A is a remote machine (the ones that issues the ssh cmd). once connected port 5497 is in listening mode on host B. host B just do a ssh 127.0.0.1 -p 5497 -l user and reaches the remote host'ssh. This can be used also for vnc and so on.


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