notebook/notes/gawk/regexp.md

title	TARGET DECK	FILE TAGS	tags
Regular Expressions	Obsidian::STEM	linux::cli gawk regexp	gawk

Overview

Most awk patterns are regular expressions delimited with /. We can use ~ and !~ to perform more complicated regexp filtering:

# Matches any line with `li` somewhere.
$ awk '/li/' data
$ awk `$0 ~ /li/` data
# Matches any line with `li` somewhere in the first field.
$ awk '$1 ~ /li/' data

awk's implementation of regexps are a superset of posix/regexp.

References

• Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. https://www.gnu.org/software/gawk/manual/gawk.pdf