Re^2:Need help understanding code snippet with "grep -f"

Well, I did read it, but I couldn't figure out what the -f does there, and how the behaviour of grep described in the docs would give me a list of existing files. But that's probably cleared up now. Is there also documentation on this "-f" thing? Because it's really hard to google for something as short as "-f"...

Comment on Re^2:Need help understanding code snippet with "grep -f"

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Re^3: Need help understanding code snippet with "grep -f" by Anonymous Monk on Dec 23, 2015 at 04:13 UTC
See -X.	[reply]
Re^3: Need help understanding code snippet with "grep -f" by Anonymous Monk on Dec 23, 2015 at 04:23 UTC
Is there also documentation on this "-f" thing? Because it's really hard to google for something as short as "-f"... yup, it can be, but here is a tip, if you use perldoc://"-f" in perlmonks search box its like "-f" site:perldoc.perl.org -> http://perldoc.perl.org/functions/-X.html	[reply]
Re^3: Need help understanding code snippet with "grep -f" by GotToBTru (Prior) on Dec 23, 2015 at 20:13 UTC
Reading this reminded me .. I had the exact same thing trip me up. -f is not a switch to the grep function but rather an independently defined function that just happens to be used as an argument here. But the unix-familiar mind sees that and thinks "grep -f" is a special form of "grep" and seeks the answer in the grep documentation. And doesn't find it. Using the block form of grep might have made this clearer. `@files = grep { -f } glob("~/data/*");` [download] But God demonstrates His own love toward us, in that while we were yet sinners, Christ died for us. Romans 5:8 (NASB)	[reply] [d/l]