find: using wildcard in -name pattern

Question

I have a simple wrapper script to play videos, where my script tries to find subtitle file to a given video file (if it exists). Given video name, I am looking for same name, only ending in .vtt extension instead of video format extension:

#!/bin/sh

video_file="$1"

sub_file="$(/bin/find -name ${video_file%.*}.*.vtt)"

if [ -f "$sub_file" ] ; then
   echo "subtitles found: $sub_file"
else
   echo "subtitles not found"
fi

If multiple sub files exist, ie: foo.en.vtt, foo.de.vtt, I want to use the first one found.

The problem is the above script only works when zero or one matching .vtt files exist. If two exist, then find returns following error:

/bin/find: paths must precede expression: `2207-_-20220620.en.vtt'
/bin/find: possible unquoted pattern after predicate `-name'?
subtitles not found

The problem seems to be that find gets two parameters for the -name predicate. But I cannot quote the pattern ${video_file%.*}.*.vtt because then the wildcard * would be interpreted literally.

I have tried using -regex predicate with same results

How can I achieve what I want in my script?

Answer 1

You wrote,

But I cannot quote the pattern ${video_file%.*}.*.vtt because then the wildcard * would be interpreted literally

I think that in this situation it's exactly what you need to do. Quoting the field stops the shell from applying it as a glob, but it allows find to see the wildcard characters in the filename pattern. (find -name understands wildcard patterns itself - see man find and search for the explanation for -name for details.)

As described in your question, let's assume that the video file is foo.mp4 and there are two subtitles files foo.de.vtt and foo.en.vtt.

You can identify both of these with this snippet

video=foo.mp4
find . -name "${video_file%.*}.*.vtt" -print

And this outputs

./foo.de.vtt
./foo.en.vtt

You said that you wanted just the first one, so with a non-POSIX extension -quit you can grab just the first:

subtitles=$(find -name "${video_file%.*}.*.vtt" -print -quit)

echo "> $subtitles"
> ./foo.de.vtt

Note that find searches in directory order and therefore does not necessarily return results in sorted order. If you can guarantee matched file names do not contain newlines you could use find … -print | sort | head -n1 to sort according to the current locale. (It's then also POSIX conformant.)