Grep multiple files using regex for specifying filenames to search for

Question

Let's say I have n files with names like link123.txt, link345.txt, link645.txt, etc.

I'd like to grep a subset of these n files for a keyword. For example:

grep 'searchtext' link123.txt link 345.txt ...

I'd like to do something like

grep 'searchtext' link[123\|345].txt

How can I mention the filenames as regex in this case?

In simple command lines, you have only filename globbing, which is a crippled kind of regex that can't handle the example you've given. You can probably write a bash script that accepts a program name (like `grep`) and a regex and does what you want. — Gene, Sep 27 '17 at 01:05

CS Pei · Answer 1 · 2017-09-29T00:19:34.733

5

you can use find and grep together like this

find . -regex '.*/link\(123\|345\).txt' -exec grep 'searchtext' {} \;

Thanks for ghoti's comment.

edited Sep 29 '17 at 00:19

answered Sep 27 '17 at 01:50

CS Pei

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As you've proposed it, this answer suffers from the same ails as [parsing ls](http://mywiki.wooledge.org/ParsingLs). If you must use `xargs`, consider find's `-print0` option along with `xargs -0`. Or better yet, use `find .. -exec`, either the traditional way or with `\+` as the command terminator so that only a single instance of `grep` needs to be run. – ghoti Sep 27 '17 at 02:36

Will Barnwell · Accepted Answer · 2017-09-27T02:00:02.447

4

You can use the bash option extglob, which allows extended use of globbing, including | separated pattern lists.

@(123|456)

Matches one of 123 or 456 once.

shopt -s extglob
grep 'searchtext' link@(123|345).txt
shopt -u extglob

edited Sep 27 '17 at 02:00

answered Sep 27 '17 at 01:52

Will Barnwell

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this solution does not seem to work on my bash 4.3.48. error is unexpected token `(` – CS Pei Sep 27 '17 at 01:55
are you setting extglob? – Will Barnwell Sep 27 '17 at 01:57
I think so. I run "shopt -s extglob" first. – CS Pei Sep 27 '17 at 01:57
oh yeah, my bad, missed an important character – Will Barnwell Sep 27 '17 at 01:58

score 0 · Answer 3 · edited Sep 27 '17 at 03:20

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I think you're probably asking for find functionality to search for filenames with regex.

As discussed here, you can easely use find . -regex '.*/link$[0-9]\{3\}$.txt' to show all these three files. Now you have only to play with regex.

PS: Don't forget to specify .*/ in the beginning of pattern.

edited Sep 27 '17 at 03:20

answered Sep 27 '17 at 02:29

tonyamjr

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score 0 · Answer 4 · answered Sep 27 '17 at 07:00

It seems, you don't need regex to determine the files to grep, since you enumerate them all (well, actually you enumerate the minimal unique part without repeating common prefix/suffix).

If regex functionality is not needed and the only aim is to avoid repeating common prefix/suffix, then simple iterating would be an option:

for i in 123 345 645; do grep searchpattern link$i.txt; done

Grep multiple files using regex for specifying filenames to search for

4 Answers4