Commands by JohnGH (6)


  • 0
    cat file | paste -s -d'%' - | sed 's/\(^\|$\)/"/g;s/%/","/g'
    JohnGH · 2013-11-12 17:48:10 15
  • 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 3
  • 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 3
  • 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 6
  • 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 3
  • 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

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Which processes are listening on a specific port (e.g. port 80)
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Split huge file into DVD+R size chunks for burning
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Delete all but the latest 5 files, ignoring directories

cat stdout of multiple commands
Concatenate the stdout of multiple commands.

Generates a TV noise alike output in the terminal
Generates a TV noise alike output in the terminal. Can be combined with https://www.commandlinefu.com/commands/view/9728/make-some-powerful-pink-noise

check open ports without netstat or lsof

Check command history, but avoid running it
!whatever will search your command history and execute the first command that matches 'whatever'. If you don't feel safe doing this put :p on the end to print without executing. Recommended when running as superuser.

Convert file type to unix utf-8
converts encoding of a file to unix utf-8 useful for data files that contain what would be usable ascii text but are encoded as mpeg or some other encoding that prevents you from doing common manipulations like 'sed'


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