Get files in bash script that contain an underscore

Question

In a directory with a bunch of files that look like this:

./test1_November 08, 2014 AM.flv
./test2.flv
./script1.sh
./script2.sh

I want to process only files that have an .flv extension and no underscore. I'm trying to eliminate the files with underscores without much luck.

bash --version
GNU bash, version 4.2.37(1)-release (x86_64-pc-linux-gnu)

script:

#!/bin/bash

FILES=$(find . -mtime 0) 
for f in "${FILES}"
do
        if [[ "$f" != *_* ]]; then
                echo "$f"
        fi
done

This gives me no files. Changing the != to == gives me all files instead of just those with an underscore. Other answers on SO indicate this should work.

Am I missing something simple here?

Don't parse the output of `find`! that's what you're missing... Use globs (as shown in anubhava's answer). — gniourf_gniourf, Nov 08 '14 at 17:54

anubhava · Accepted Answer · 2014-11-08T18:03:00.610

5

You can use this extended glob pattern:

shopt -s extglob
echo +([^_]).flv

+([^_]) will match 1 or more of any non underscore character.

Testing:

ls -l *flv
-rw-r--r-- 1 user1 staff 0 Nov  8 12:44 test1_November 08, 2014 AM.flv
-rw-r--r-- 1 user1 staff 0 Nov  8 12:44 test2.flv

echo +([^_]).flv
test2.flv

To process these files in a loop use:

for f in +([^_]).flv; do
   echo "Processing: $f"
done

PS: Not sure you're using -mtime 0 in your find as my answer is for the requiremnt:

I want to process only files that have an .flv extension and no underscore

edited Nov 08 '14 at 18:03

answered Nov 08 '14 at 17:46

anubhava

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Definitely the best approach. You should explicit how to do a loop on these files. – gniourf_gniourf Nov 08 '14 at 17:55
Oh, I overlooked the `-mtime 0` in OP... that would be more difficult to achieve with globs... – gniourf_gniourf Nov 08 '14 at 17:57
Actually I am not sure why OP is using `-mtime 0` because OP wrote requirement as: **I want to process only files that have an .flv extension and no underscore** – anubhava Nov 08 '14 at 17:58
1

I'm confused too about OP. – gniourf_gniourf Nov 08 '14 at 17:59
The mtime was to get files modified in the last 24 hours – Andrew Grothe Nov 08 '14 at 19:34
1

This works very well and is short and to-the-point as well. If I still need to work with the file mtime I can do so inside the loop but as per my request, this is awesome. – Andrew Grothe Nov 08 '14 at 19:50

score 4 · Answer 2 · edited Nov 08 '14 at 18:18

4

You can pass multiple patterns to find and include a not

find . -name "*.flv" -not -name "*_*"

You can loop over the results of find by piping it into a while

find -name "*.flv" -not -name "*_*" -print0 | while IFS= read -r -d '' filename; do
    echo "$filename"
done

or you can forgo the loop completely and use xargs

find -name "*.flv" -not -name "*_*" -print0 | xargs -0 -n1 echo

edited Nov 08 '14 at 18:18

gniourf_gniourf

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answered Nov 08 '14 at 17:47

Leon

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Good answer. You should show the OP how to perform a loop on the result of `find` (with `-print0` and the appropriate `read`), with the caveat that `-print0` is not POSIX. – gniourf_gniourf Nov 08 '14 at 17:58
@gniourf_gniourf I like the way you think, but I'm not entirely sure what the OP wants to do. I have found that a lot of people who want to loop can actually get away with `xargs` instead – Leon Nov 08 '14 at 18:02
1

Then show both options `;)` or ask OP to clarify what he's trying to achieve. – gniourf_gniourf Nov 08 '14 at 18:04
@gniourf_gniourf not sure if I missed something there :D – Leon Nov 08 '14 at 18:15
1

No problem, I fixed that for you. – gniourf_gniourf Nov 08 '14 at 18:18
@gniourf_gniourf I've been schooled :) – Leon Nov 08 '14 at 18:20
I don't really need a loop, just need to process each file in a result set. – Andrew Grothe Nov 08 '14 at 19:33

score 1 · Answer 3 · edited Nov 08 '14 at 18:26

1

The problem is this line:

for f in "${FILES}"

The quotes are preventing word splitting, so entire list of filenames is being processed as a single item. What you want is:

IFS=$'\n'
for f in $FILES

The IFS setting makes it use newlines as the word delimiters, so you can have filenames with spaces in them.

A better way to write loops like this is to avoid using the variable:

find ... | while read -r f
do
    ...
done

edited Nov 08 '14 at 18:26

gniourf_gniourf

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answered Nov 08 '14 at 17:49

Barmar

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And you're subject to pathname expansion if filenames contain wildcards or square brackets. So you should also add the `set -f` somewhere... that's becoming a bit clunky. – gniourf_gniourf Nov 08 '14 at 18:08
@gniourf_gniourf I've added a `find | while read` loop to show how to do this without requiring any word splitting. – Barmar Nov 08 '14 at 18:24

Get files in bash script that contain an underscore

3 Answers3