Unix Commands I Love

I’ve been spending more time lately increasing my knowledge of unix commands in order to make my daily log parsings, etc easier. I’ve found that I have a lot of commands that I use out of habit and they get things done, but not necessarily in the best way. So I thought I’d write about a few of my favorite new commands.

watch

The watch command is great for monitoring something for a change, or just to keep an open status.

You can do something simple just to keep a terminal session active

watch -n 60 date

or something more complex like generating a small report from log output

watch -n 30 'echo "SUCCESS"; grep -ic "success" results.log; echo "SKIPPED"; grep -icv "success" results.log; echo "TOTAL"; wc -l results.log;

this will generate a nice little report like:

SUCCESS
13886
SKIPPED
114
TOTAL
14000 results.log

the -n [sec] argument defines how frequently to update the data. At that interval the screen will refresh and the updated info displayed.

awk

I have several awk one liners that I use almost daily

• Yank a specific record from an LDIF

  gawk 'BEGIN {IGNORECASE=1; RS="\n\n"} /cn: Brian Kohles/ {print ; print "";} example.ldif
  

• Count occurences column 1 ($1) in a file

  awk '{count[$1]++} END {for(j in count) print j,"\t" count[j]}'
  

• Split a file into multiple 1000 line files

  awk 'NR%1000 == 1 {file = "outputfile" i++} {print > file}' file.txt