gistfile1.sh

#!/bin/bash

if [ ${#} != 1 ] ; then
    echo "Usage ${0/*\/} file"
    exit
fi

file=$1
ext=${file/*./}
sub_id=$(mkvinfo ${file} | awk '
         BEGIN { id=0 } {
            if ( $0 ~ /mkvextract:/ ){
                 gsub(/)/,"")
                 id=$NF
            } else if ( $0 ~ /Codec ID: S_TEXT/){
                print id
            }
         }')

if [ ! -h "${file/$ext/avi}" ] ; then
    ln -s $file ${file/$ext/avi}
fi
mkvextract tracks ${file} ${sub_id}:${file/$ext/srt}
ls -lart ${file} ${file/$ext/avi} ${file/$ext/srt}