Commands using perl (369)

  • modify a file in place with perl

    changes THIS to THAT in all files matching fileglob* without using secondary files


    2
    perl -pi -e 's/THIS/THAT/g' fileglob*
    elofland · 2009-02-05 19:19:52 60
  • The top ten commands you use

    Show Sample Output


    2
    perl -pe 's/.+;//' ~/.zsh_history | sort | uniq -c | sort -r|head -10
    aoiaoi · 2009-02-06 15:24:32 166
  • re-assign line numbers

    Show Sample Output


    2
    perl -pe 's/\d+/++$n/e' file.txt
    mikeda · 2009-02-17 14:51:31 6
  • Comma insertions

    Insert a comma where necessary when counting large numbers. I needed to separate huge amounts of packets and after 12+ hours of looking in a terminal, I wanted it in readable form. Show Sample Output


    2
    perl -pe '$_=reverse;s/\d{3}(?=\d)(?!.*?\.)/$&,/g;$_=reverse'
    sil · 2009-02-18 16:34:18 15
  • Recursive Search and Replace

    Finds the string in every file in an entire directory and all its subdirectories and replaces it with a new string. Especially useful when changing a machine's IP address or hostname - run it on /etc.


    2
    perl -pi -e's/<what to find>/<what to replace it with>/g' `grep -Rl <what to find> /<dir>/*`
    adampbell · 2009-02-26 19:14:39 8
  • make a list of movies(.m3u).


    2
    find $HOME -type f -print | perl -wnlaF'/' -e 'BEGIN{ print "#EXTM3U"; } /.+\.wmv$|.+\.mpg$|.+\.vob$/i and print "#EXTINF:$F[-1]\nfile://$&";' > movies.m3u
    ishiduca · 2009-02-28 12:17:41 4
  • Prints any IP out of a file


    2
    perl -ne 'while (/([0-9]+\.){3}[0-9]+/g) {print "$&\n"};' file.txt
    P17 · 2009-04-01 13:49:46 6
  • Connect to all running screen instances

    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
  • Replace Every occurrence of a word in a file

    Replace 'this' with 'that'


    2
    perl -p -i -e 's/this/that/g' filename
    rader5 · 2009-08-09 20:53:50 8
  • show the real times iso of epochs for a given column

    When you have one of those (log)files that only has epoch for time (since no one will ever look at them as a date) this is a way to get the human readable date/time and do further inspection. Mostly perl-fu :-/


    2
    perl -F' ' -MDate::Format -pale 'substr($_, index($_, $F[1]), length($F[1]), time2str("%C", $F[1]))' file.log
    coffeeaddict_nl · 2009-08-13 13:57:33 4
  • convert unixtime to human-readable


    2
    perl -e 'print scalar(gmtime(1234567890)), "\n"'
    andrew112358 · 2009-08-25 15:00:52 4
  • Go get those photos from a Picasa album


    2
    wget 'link of a Picasa WebAlbum' -O - |perl -e'while(<>){while(s/"media":{"content":\[{"url":"(.+?\.JPG)//){print "$1\n"}}' |wget -w1 -i -
    aciancone · 2009-09-27 14:36:27 7
  • A command line calculator in Perl

    Once I wrote a command line calculator program in C, then I found this... and added to it a bit. For ease of use I normally use this in a tiny Perl program (which I call pc for 'Perl Calculator') #!/usr/bin/perl -w die "Usage: $0 MATHS\n" unless(@ARGV);for(@ARGV){s/x/*/g;s/v/sqrt /g;s/\^/**/g}; print eval(join('',@ARGV)),$/; It handles square roots, power, modulus: pc 1+2 (1 plus 2) 3 pc 3x4 (3 times 4) 12 pc 5^6 (5 to the power of 6) 15625 pc v 49 ( square root of 49 ) 7 pc 12/3 (12 divided by 3) 4 pc 19%4 (19 modulus 4) 3 (you can string maths together too) pc 10 x 10 x 10 1000 pc 10 + 10 + 10 / 2 25 pc 7 x v49 49 Show Sample Output


    2
    perl -e 'for(@ARGV){s/x/*/g;s/v/sqrt /g;s/\^/**/g};print eval(join("",@ARGV)),$/;'
    JohnGH · 2009-12-21 21:03:27 9
  • Recursively grep for string and format output for vi(m)

    This is a big time saver for me. I often grep source code and need to edit the findings. A single highlight of the mouse and middle mouse click (in gnome terminal) and I'm editing the exact line I just found. The color highlighting helps interpret the data.


    2
    mgc() { grep --exclude=cscope* --color=always -rni $1 . |perl -pi -e 's/:/ +/' |perl -pi -e 's/^(.+)$/vi $1/g' |perl -pi -e 's/:/ /'; }
    stinkerweed999 · 2010-01-26 17:00:01 4
  • Get your commandlinefu points (upvotes - downvotes)

    Like command #4845, prints score, number of entries, and average score.


    2
    username=bartonski;curl -s http://www.commandlinefu.com/commands/by/$username/json|perl -e 'BEGIN{$s=0;$n=0};END{print "Score: $s\nEntries: $n\nMean: ";printf "%3.2f\n",$s/$n}' -0173 -nae 'foreach $f (@F){if($f =~ /"votes":"(-*\d+)"/){$s += $1; $n++;}}'
    bartonski · 2010-02-16 01:03:29 4
  • Update twitter with Perl

    Requires Net::Twitter. Just replace the double quoted strings with the appropriate info.


    2
    perl -MNet::Twitter -e '$nt = Net::Twitter->new(traits => [qw/API::REST/], username => "YOUR USERNAME", password => "YOUR PASSWORD"); $ud = $nt->update("YOUR TWEET");'
    dbbolton · 2010-06-16 19:46:05 4
  • diff files while disregarding indentation and trailing white space

    **NOTE** Tekhne's alternative is much more succinct and its output conforms to the files actual contents rather than with white space removed My command on the other hand uses bash process substitution (and "Minimal" Perl), instead of files, to first remove leading and trailing white space from lines, before diff'ing the streams. Very useful when differences in indentation, such as in programming source code files, may be irrelevant Show Sample Output


    2
    diff <(perl -wpl -e '$_ =~ s/^\s+|\s+$//g ;' file1) <(perl -wpl -e '$_ =~ s/^\s+|\s+$//g ;' file2)
    jemptymethod · 2010-10-06 19:14:42 5
  • Decode base64-encoded file in one line of Perl

    If you are in an environment where you don't have the base64 executable or MIME tools available, this can be very handy for salvaging email attachments when the headers are mangled but the encoded document itself is intact.


    2
    perl -MMIME::Base64 -ne 'print decode_base64($_)' < file.txt > out
    dmmst19 · 2010-12-13 23:35:20 3
  • Find C/C++ source code comments

    This is a naive way of finding source code comments in source code files that use C-like comments: // and /*...*/


    2
    perl -e 'my $in_comment = 0; while (<>) { $in_comment = 1 if m{\Q/*\E}; print if $in_comment; $in_comment = 0 if m{\Q*/\E}; }' *.cpp
    doherty · 2011-07-08 00:17:27 4
  • Find default gateway (proper at ppp connections too)


    2
    route -n | perl -ne '$ANY="0.0.0.0"; /^$ANY/ and split /\s+/ and print "Gateway to the World: ",($_[1]!=$ANY)?$_[1]:(`ip address show $_[$#_]`=~/peer ([0-9\.]+)/ and $1),", via $_[$#_].\n"'
    bandie91 · 2011-09-13 08:05:58 5
  • FizzBuzz One-liner


    2
    perl -le 'print$_%3?$_%5?$_:"Buzz":$_%5?"Fizz":"FizzBuzz"for 1..100'
    depesz · 2012-01-10 13:10:30 5
  • Remove a range of lines from a file

    Show Sample Output


    2
    perl -i -ne 'print if $. == 3..5' <filename>
    bashrc · 2012-01-27 23:15:10 4
  • Apache CLF access log format to CSV converter

    - excel date compatible with a separate hour field - added a fixed 1 for easier request counter aggregation - split URL in directory, filename, fileext, query - used with tomcat valve with response bytes replaced by elapsed time Show Sample Output


    2
    #(see sample) $ cat x | perl -pe 'BEGIN{ print "TIME;...\n"; } s!(\S+) - (\S+) - \[(\d\d)/(\S\S\S)/(\S+):(\d\d):(\d\d:\d\d) \S+\] "(\S+) (.*/)(\S+)(?:\.([^?]*)(\?\S*)?) HTTP/\S+" (\d+) (\S+)!$3-$4-$5 $6:$7;$6;$2;$1;$8;$13;1;$14;$11;$10;$9;$12;!' > x.csv
    hute37 · 2012-02-10 16:58:50 3
  • Text graphing ping output filter

    Nasty perl one-liner that provides a sparkline of ping times. If you want a different history than the last 30, just put that value in. It (ab)uses unicode to draw the bars, inspired by https://github.com/joemiller/spark-ping . It's not the most bug-free piece of code, but what it lacks in robustness it makes up for in capability. :) If anyone has any ideas on how to make it more compact or better, I'd love to hear them. I included a ping to google in the command just as an example (and burned up 10 chars doing it!). You should use it with: $ ping example.com | $SPARKLINE_PING_COMMAND Show Sample Output


    2
    ping g.co|perl -ne'$|=/e=(\S+)/||next;(push@_,$1)>30&&shift@_;print"\r",(map{"\xe2\x96".chr(128+7*$_/(sort{$b<=>$a}@_)[0])." "}@_),"$1ms"'
    bartgrantham · 2012-07-06 22:42:06 3
  • MPD + Digitally Imported

    1.- Enter into the playlist path. 2.- Run the command. 3.- Playlists created!


    2
    wget -q -O - http://listen.di.fm/public2 | sed 's/},{/\n/g' | perl -n -e '/"key":"([^"]*)".*"playlist":"([^"]*)"/; print "$1\n"; system("wget -q -O - $2 | grep -E '^File' | cut -d= -f2 > di_$1.m3u")'
    Zort · 2013-02-20 03:37:41 9
  • ‹ First  < 2 3 4 5 6 >  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

list all opened ports on host
in loop, until the last port (65535), list all opened ports on host. in the sample I used localhost, but you can replace with any host to test.

Benchmark SQL Query
Benchmark a SQL query against MySQL Server. The example runs the query 10 times, and you get the average runtime in the output. To ensure that the query does not get cached, use `RESET QUERY CACHE;` on top in the query file.

convert unixtime to human-readable with awk
- convert unixtime to human-readable with awk - useful to read logfiles with unix-timestamps, f.e. squid-log: sudo tail -f /var/log/squid3/access.log | awk '{ print strftime("%c ", $1) $0; }

Push your present working directory to a stack that you can pop later
If are a Bash user and you are in a directory and need to go else where for a while but don't want to lose where you were, use pushd instead of cd. cd /home/complicated/path/.I/dont/want/to/forget pushd /tmp cd thing/in/tmp popd (returns you to /home/complicated/path/.I/dont/want/to/forget)

Create a persistent connection to a machine
Create a persistent SSH connection to the host in the background. Combine this with settings in your ~/.ssh/config: Host host ControlPath ~/.ssh/master-%r@%h:%p ControlMaster no All the SSH connections to the machine will then go through the persisten SSH socket. This is very useful if you are using SSH to synchronize files (using rsync/sftp/cvs/svn) on a regular basis because it won't create a new socket each time to open an ssh connection.

For finding out if something is listening on a port and if so what the daemon is.
See what's listening on your IPv4 ports on FreeBSD.

List Threads by Pid along with Thread Start Time
This command will list all threads started by a particular pid along with the start time of each thread. This is very valuable when diagnosing thread leaks.

Notepad in a browser
A commandline version of the notepad in a browser: http://www.commandlinefu.com/commands/view/12161/notepad-in-a-browser-type-this-in-the-url-bar All credit to the origional author of this fantastic command, whos only failing as most of the comments pointed out was that it wasn't a command... well, now its a command. Send all upvotes to dtlp747.

Find a CommandlineFu users average command rating

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"

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: