Question

Was wondering if someone could help me out with regular expressions and bash.

I’m trying to execute a set of commands on files that only have a certain extension, in this case: mpg, mpeg, avi, and mkv.

I’ve actually found a solution here, however, it doesn’t seem to work. If someone can tell me why, I’d appreciate it.

#!/bin/bash

# Configuration
TARGETDIR="$1"
TARGETEXT="(mpg|mpeg|avi|mkv)"

for d in `find $1 -type d`
do
    echo "Searching directory: $d"

    for f in "$d"/*
    do
            if [ -d "${f}" ];
            then
                    # File is a directory, do not perform
                    echo "$f is a directory, not performing ..."
            elif [ -f "${f}" ]; 
            then
                    filename=$(basename "$f")
                    extension="${filename##*.}"
                    if [ "$extension" == "$TARGETEXT" ];
                    then
                            echo "Match"
                    else
                            echo "Mismatch - $f - $extension"
                    fi
            fi
    done
done

Again, any assistance is appreciated.

Answer 1

Instead of direct string comparison

if [ "$extension" == "$TARGETEXT" ];

use Bash regex matching syntax

if [[ "$extension" =~ $TARGETEXT ]];

Note the double [[ ]] and the non-quoted $TARGETEXT.