[SOLVED] Use each line of file as part of regex

Issue

I have a file with a simple string on each line...

bob
fred
sally

I want to use each string as part of a regex

grep -r "regex using <bob>" (value from line 1)
grep -r "regex using <fred>" (value from line 2
grep -r "regex using <sally>" (value from line 3)

I expect to use the file strings in various regex's so not wanting to edit original file. Preferably just using pipes, or creating a temp file if that's a must.

Solution

sed 's/.*/regex using <&>/' file-with-strings | grep -f- file-to-search

Basically use sed to wrap each line of file-with-strings in your regex, then pipe it to grep -f- which will read regexes from stdin

Or:

grep -P "regex using <$(tr '\n' '|' file-with-strings)>" file-to-search

... which will do what you want in the comments: assemble bob|fred|sally and wrap it in your regex. Requires bash or similar for $() syntax.

Answered By - stevesliva

Answer Checked By - Mary Flores (WPSolving Volunteer)