Getting a group of lines from a file

May 19, 2014 · Comments
codetips awkbash

I’ve had this need quite a few times to pull out a section of logs that would begin with a particular line and end with another. grep is not exactly useful there because it only prints out sections based on line counters (using -A/B/C) lines based on a single search pattern.

I came up with a script that can run at almost same speeds using grep/cat/awk. awk is used to decide whether the end of the section has been reached or not. Some features of the script are:

• Since awk script only toggles one variable it works seamlessly without delaying the actual work

• Works on gzip files as well

• If you do not want to depend on grep or are unsure how many lines may be between begin and end keyword then replace gunzip with zcat and grep with cat.

• Usage: group filename printBeginKeyword printUntilKeyword NumOfLines

Let’s have a look at the script….