Hello,
I added an option to grep that filters files through a specified program. The
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
receive each file through stdin and its stdout will be used in lieu of the
file. Any valid shell command can be used instead of zcat.
This is better than the zgrep commands provided by the gzip, bzip2 and xz
projects, 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 option
to grep. This is longer to type our than `-Z` or `-J`, but it also provides 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 useful to
point it out.
I have a patch that I can send. I believe my patch is trivial, the only part
that's longer than 3 lines is a simple fork-exec pattern (40 lines including
whitespace, but they're the same you've seen in plenty of other programs). 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 doing
something wrong!
