Commands by JohnGH (6)


  • 0
    cat file | paste -s -d'%' - | sed 's/\(^\|$\)/"/g;s/%/","/g'
    JohnGH · 2013-11-12 17:48:10 2
  • Awk magic to replace: cat /etc/sybase/interfaces | grep -A 1 -e "$SEARCH" | grep query | awk '{ print $4 }' | awk -F'.' '{print $2}'


    0
    awk '/^'$SEARCH'[ ]*$/{getline;if ($1 ~ /query/) {split($4,a,".");print a[2]}}' /etc/sybase/interfaces
    JohnGH · 2010-12-17 13:24:27 0
  • If you don't have nl on your system, this achieves a similar effect, the default behavior in nl is to not number blank lines, but this does.


    2
    grep -n "^" <filename>
    JohnGH · 2010-01-07 14:54:29 0
  • I needed to add a line to my crontab from within a script and didn't want to have to write my own temporary file. You may find you need to reload the crond after this to make the change take effect. e.g.: if [ -x /sbin/service ] then /sbin/service crond reload else CRON_PID=`ps -furoot | awk '/[^a-z]cron(d)?$/{print $2}'` if [ -n "$CRON_PID" ] then kill -HUP $CRON_PID fi fi The reason I had CRON_HOUR and CRON_MINS instead of numbers is that I wanted to generate a random time between midnight & 6AM to run the job, which I did with: CRON_HOUR=`/usr/bin/perl -e 'printf "%02d\n", int(rand(6))'` CRON_MINS=`/usr/bin/perl -e 'printf "%02d\n", int(rand(60));'`


    -1
    crontab -l | sed -e '$G;$s-$-'"$CRON_MINS $CRON_HOUR"' * * * /usr/bin/command >/dev/null 2>&1-' | crontab -
    JohnGH · 2010-01-07 11:00:05 0
  • print the lines of a file in randomized order Show Sample Output


    0
    perl -wl -e '@f=<>; for $i (0 .. $#f) { $r=int rand ($i+1); @f[$i, $r]=@f[$r,$i] if ($i!=$r); } chomp @f; print join $/, @f;' try.txt
    JohnGH · 2009-12-21 21:15:55 0
  • 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 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

List complete size of directories (do not consider hidden directories)
why make it complicated ? : ] -------------------- I just noticed someone else has posted this on this site before me (sorry I am now a duplicate :/) http://www.commandlinefu.com/commands/view/4313

get bofh excuse from a trusted source :-)

copy file to clipboard
Loads file content on clipboard. Very useful when text selection size is higher than console size.

Watch the progress of 'dd'
Only slightly different than previous commands. The benefit is that your "watch" should die when the dd command has completed. (Of course this would depend on /proc being available)

purge all packages marked with 'rc'
After you install/remove lots of packages, there are many packages marked with 'rc'. This script help you to purge these packages, it will save some spaces from your disk.

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"

Show errors in the kernel ring buffer
Much more useful then parsing syslog

Find the package that installed a command

Simplification of "sed 'your sed stuff here' file > file2 && mv file2 file"

Change framebuffer font
setfont load vga console font. The default font directory is usually in /lib/kbd/consolefonts. Setfont is part of kbd package. Tested on CentOS.


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: