GNU bug report logs - #70511
Option to grep into compressed files

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Date: Sun, 21 Apr 2024 16:46:17 +0000
To: "bug-grep@HIDDEN" <bug-grep@HIDDEN>
From: Mary <marycada@HIDDEN>
Subject: Option to grep into compressed files
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Hello,

I added an option to grep that filters files through a specified program. T=
he main purpose for that is to uncompress files using the zcat (or `gzip -d=
`) command, or an equivalent for another compression format.

It works like this:

    grep -j zcat pattern textfile.gz [textfile2.gz...]

(I chose `-j` for no particular reason. Any unused letter could go there.)

This will spawn a shell and execute the given command (zcat), which will re=
ceive each file through stdin and its stdout will be used in lieu of the fi=
le. Any valid shell command can be used instead of zcat.

This is better than the zgrep commands provided by the gzip, bzip2 and xz p=
rojects, because it supports all of the options, including `-r`.

It can also be used with arbitrary commands, like less popular compression =
algorithms or even commands unrelated to compression. I read at https://www=
.gnu.org/software/grep/devel.html that there were plans to add `-Z` and `-J=
` options for gzip and bzip2; my implementation can support any algorithm.

The problem I see with that though is that it would add a shell command opt=
ion to grep. This is longer to type our than `-Z` or `-J`, but it also prov=
ides a shell access to anybody who can control what options grep receives. =
In practice, I'm not sure how serious that is, but I thought it would be us=
eful to point it out.

I have a patch that I can send. I believe my patch is trivial, the only par=
t that's longer than 3 lines is a simple fork-exec pattern (40 lines includ=
ing whitespace, but they're the same you've seen in plenty of other program=
s). I know there are specific requirements regarding copyright, and I don't=
 want to cause problems about that (I can't sign the FSF's documents). May =
I send my patch?

-- Mary

PS- This is my first time using a mailing list, please let me know if I'm d=
oing something wrong!