Commands using perl (369)

  • Pick a random line from a file

    This is from perldoc -q random.*line, which says: This has a significant advantage in space over reading the whole file in. You can find a proof of this method in The Art of Computer Programming, Volume 2, Section 3.4.2, by Donald E. Knuth. Who am I to argue with Don Knuth?


    1
    perl -e 'rand($.) < 1 && ($line = $_) while <>;'
    unixmonkey20842 · 2011-04-25 21:28:26 3
  • Perl Command Line Interpreter

    Can also just use the debug mode like this. Show Sample Output


    1
    perl -dwe 1
    bashrc · 2011-05-05 20:28:03 6
  • Mark packages installed with build-dep for autoremove (on Debian/Ubuntu)

    Replace PACKAGE with desired package name. Found here: http://mikebeach.org/2011/04/undo-apt-get-build-dep/


    1
    sudo aptitude markauto $(apt-cache showsrc PACKAGE | grep Build-Depends | perl -p -e 's/(?:[\[(].+?[\])]|Build-Depends:|,|\|)//g')
    Lexton · 2011-05-08 14:18:52 6
  • Delete empty directories

    Recursively delete empty directories. Use with care.


    1
    perl -MFile::Find -e"finddepth(sub{rmdir},'.')"
    igorfu · 2011-05-23 08:45:34 7
  • Scan for [samba|lanman] NetBIOS names and ip addresses in LAN by ARP.


    1
    arp-scan -I eth0 -l | perl -ne '/((\d{1,3}\.){3}\d{1,3})/ and $ip=$1 and $_=`nmblookup -A $ip` and /([[:alnum:]-]+)\s+<00>[^<]+<ACTIVE>/m and printf "%15s %s\n",$ip,$1'
    bandie91 · 2011-07-08 07:41:41 3
  • Syntax Highlight your Perl code


    1
    perl -mText::Highlight -E 'say Text::Highlight->new(ansi => 1)->highlight(Perl => do { local (@ARGV,$/) = shift; <> }) ' path/to/perl-file.pl
    dbr · 2011-07-12 04:55:12 5
  • change microdvd subtitles framerate

    this command example converts to 25 fps subtitles that were originally created for 24 fps movie


    1
    cat subtitles.txt | perl -pe 's/} /}/g; s/{(\d+)}/=1=/; $f1=(24/25*$1); s/{(\d+)}/=2=/; $f2=(24/25*$1); $f1=~s/\..*//; $f2=~s/\..*//; s/=1=/{$f1}/; s/=2=/{$f2}/; ' > subtitles_newfps.txt
    ciekawy · 2011-07-30 15:34:43 18
  • Lookup errno defintions

    Calls the POSIX strerror() function to look up the meaning of integer ERRNOs set by some functions.


    1
    perl -MPOSIX -e 'print strerror($ARGV[0])."\n";' ERRNO
    sethjust · 2011-09-21 18:16:19 5
  • Multiline Search/Replace with Perl

    from http://stackoverflow.com/questions/1030787/multiline-search-replace-with-perl added greedy trick in wildcard match (.*?) from http://www.troubleshooters.com/codecorn/littperl/perlreg.htm#Greedy Show Sample Output


    1
    perl -i -pe 'BEGIN{undef $/;} s/START.*?STOP/replace_string/smg' file_to_change
    hute37 · 2011-10-05 11:22:36 10
  • one-line log format for svn

    the output of svn log is annoying to grep, since it spreads the useful info over multiple lines. This compacts the output down to one line so eg you can grep for a comment and see the rev, date & committer straight away. Updated: MUCH shorter, easier to remember. Now it just replaces newlines with spaces, except on '---' lines. Show Sample Output


    1
    svn log | perl -l40pe 's/^-+/\n/'
    bazzargh · 2011-10-14 16:02:22 6
  • wc in perl


    1
    perl -ane 'END{printf(" %d %d %d\n", $x, $y, $z)} $x+=1; $y+=@F; $z+=length' file.txt
    kev · 2011-10-24 06:14:02 10
  • Create new user with home dir and given password

    The crypt function takes a password, key, as a string, and a salt character array which is described below, and returns a printable ASCII string which starts with another salt. It is believed that, given the output of the function, the best way to find a key that will produce that output is to guess values of key until the original value of key is found. from http://en.wikipedia.org/wiki/Crypt_(Unix)


    1
    useradd -m -p $(perl -e'print crypt("passwordscelta", "stigghiola")') user
    0disse0 · 2012-02-06 19:53:01 7
  • One line Perl Script to determine the largest file sizes on a Linux Server

    This one line Perl script will display the smallest to the largest files sizes in all directories on a server. Show Sample Output


    1
    du -k | sort -n | perl -ne 'if ( /^(\d+)\s+(.*$)/){$l=log($1+.1);$m=int($l/log(1024)); printf ("%6.1f\t%s\t%25s %s\n",($1/(2**(10*$m))),(("K","M","G","T","P")[$m]),"*"x (1.5*$l),$2);}' | more
    Q_Element · 2012-02-07 15:49:19 10
  • Tracklist reaplace backspace to '-'

    Requires perl 5.14 or greater


    1
    perl -e 'rename $_, s/ /-/gr for <*.mp3>'
    ironcamel · 2012-02-21 17:07:18 4
  • Perl oneliner to print access rights in octal format

    This prints file access rights in octal - useful when "stat" is unavailable. Show Sample Output


    1
    perl -e 'printf "%04o\n", (stat shift)[2] & 0777;' file
    zlemini · 2012-03-22 15:05:04 9
  • multiline data block parse and CSV data extraction with perl

    extract data in multiline blocks of data with perl pattern matching loop Show Sample Output


    1
    cat z.log | perl -ne 'BEGIN{ print "DATE;RATE\n"; } /\[(\d.*)\]/ && print $1; /CURRENT RATE: +(\S+) msg.*/ && print ";" .$1 . "\n"; '
    hute37 · 2012-04-03 13:52:20 3
  • Perl One Liner to Generate a Random IP Address


    1
    perl -e 'printf "00:16:3E:%02X:%02X:%02X\n", rand 0xFF, rand 0xFF, rand 0xFF'
    Gular · 2012-07-02 09:59:43 5
  • Encode file path to URL

    Really helpfull when play with files having spaces an other bad name. Easy to store and access names and path in just a field while saving it in a file. This format (URL) is directly supported by nautilus and firefox (and other browsers) Show Sample Output


    1
    convert_path2uri () { echo -n 'file://'; echo -n "$1" | perl -pe 's/([^a-zA-Z0-9_\/.])/sprintf("%%%.2x", ord($1))/eg' ;} #convert2uri '/tmp/a b' ### convert file path to URI
    totti · 2013-07-01 08:54:45 7
  • Update a namecheap @ A record to point to your current internet-facing IP address

    Sets the @ A record for your domain hosted by namecheap to your current internet-facing IP address, logs success or failure with syslog, and logs the data returned to /root/dnsupdate. Change the XXX's as appropriate. More info at: http://www.namecheap.com/support/knowledgebase/article.aspx/29/ Show Sample Output


    1
    logger -tdnsupdate $(curl -s 'https://dynamicdns.park-your-domain.com/update?host=@&domain=xxx&password=xxx'|tee -a /root/dnsupdate|perl -pe'/Count>(\d+)<\/Err/;$_=$1eq"0"?"Update Sucessful":"Update failed"'&&date>>/root/dnsupdate)
    MagisterQuis · 2013-08-11 16:27:39 7
  • send raw data (hex written)using UDP to an IP and port

    Use it to send raw data to a networked device. Used to interact with relay controller board whose documentation is lost, so use wireshark to sniff the sent data and replayed using the command.


    1
    echo -n 023135 | perl -pe 's/([0-9a-f]{2})/chr hex $1/gie' | nc -4u -q1 -p5001 192.168.0.100 2000
    sucotronic · 2013-09-18 14:31:47 7
  • Convert control codes to visible Unicode Control Pictures

    Converts control codes and spaces (ASCII code ≤ 32) to visible Unicode Control Pictures, U+2400 ? U+2420. Skips \n characters, which is probably a good thing. Show Sample Output


    1
    /bin/echo -e '\002Hello, Folks\t!\r' | perl -pwle 'use v5.14; s/([\N{U+0000}-\N{U+0020}])/chr(9216+ord($1))/ge;'
    scruss · 2014-06-30 01:45:40 11
  • drop first column of output by piping to this

    An advantage is that this doesn't modify remained string at all. One can change {0,1} with {0,n} to drop several columns


    1
    perl -pE's/(\S+\s*){0,1}//'
    pung96 · 2015-05-09 15:14:58 12
  • Get all shellcode on binary file from objdump

    Better than the others, and actually works unlike some of them. Show Sample Output


    1
    objdump -d $1 | grep -Po '\s\K[a-f0-9]{2}(?=\s)' | sed 's/^/\\x/g' | perl -pe 's/\r?\n//' | sed 's/$/\n/'
    Daytona · 2015-05-23 01:21:58 10
  • Get the SAN (subjectAltName) of a site's certificate.

    Based on http://stackoverflow.com/questions/13127352/checking-alternative-names-for-a-san-ssl-cert Replace "facebook.com" with the desired hostname. Show Sample Output


    1
    echo "quit" | openssl s_client -connect facebook.com:443 | openssl x509 -noout -text | grep "DNS:" | perl -pe "s/(, )?DNS:/\n/g"
    lgarron · 2015-08-13 22:50:45 9
  • Find all file extension in current dir.


    1
    find . -type f | perl -ne 'print $1 if m/\.([^.\/]+)$/' | sort -u
    wuseman1 · 2018-11-11 01:09:42 538
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check open ports without netstat or lsof

Fill a hard drive with ones - like zero-fill, but the opposite :)
Note: Replace 200000 with drive bytes/512, and /dev/sdx with the destination drive/partition. ;) Note: You may need to install pipebench, this is easy with "sudo apt-get install pipebench" on Ubuntu. The reason I hunted around for the pieces to make up this command is that I wanted to specifically flip all of the bits on a new HDD, before running an Extended SMART Self-Test (actually, the second pass, as I've already done one while factory-zeroed) to ensure there are no physical faults waiting to compromise my valuable data. There were several sites that came up in a Google search which had a zero-fill command with progress indicator, and one or two with a fill-with-ones command, but none that I could find with these two things combined (I had to shuffle around the dd command(s) to get this to happen without wasting speed on an md5sum as well). For reference, these are the other useful-looking commands I found in my search: Zero-fill drive "/dev/sdx", with progress indicator and md5 verification (run sudo fdisk -l to get total disk bytes, then divide by 512 and enter the resulting value into this command for a full wipe) $ dd if=/dev/zero bs=512 count= | pipebench | sudo tee /dev/sdx | md5sum And this command for creating a file filled with ones is my other main source (besides the above command and man pages, that is - I may be a Linux newbie but I do read!): $ tr '\000' '\377' < /dev/zero | dd of=allones bs=1024 count=2k Hope someone finds this useful! :) Cheers, - Gliktch

View webcam output using GStreamer pipeline
Open a window that displays camera capture. Framerate, width and height may be changed to match your needs.

perl one-liner to get the current week number
Not perl but shorter.

Get a list of all your VirtualBox virtual machines by name and UUID from the shell
A similar command that lists only the currently running VMs is thus: $ VBoxManage list runningvms ...the above showing a list of VMs by name and UUID in the same format as the "$ VBoxManage list vms" command

fetch all revisions of a specific file in an SVN repository
exported files will get a .r23 extension (where 23 is the revision number)

Edit file(s) that has been just listed
That will open vi with the four README files in different viewports. Specially handy when you find there is only one file matching your pattern and you don't want to specify the full path.

burn initial session on a growable DVD using growisofs
replace "directory name to burn on DVD" with actual directory name that you want to copy on DVD

nagios wrapper for any script/cron etc
use w/ check_freshness. passes the last line of output and exit code to nagios via nsca

Create a directory and go inside it
$_ expands to the last argument of the last command that was executed

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