[Example about doing regular expression match via Bash] Bash doesn't support non-greedy regex like (.*?)

regex.sh

str="asdkljfgaskdlgjkladsjfg123_abc_d4e5#asdfgerhgreg"
regex="[0-9]+_([a-z]+)_[0-9a-z]*"

if [[ $str =~ $regex ]]
then
    name="${BASH_REMATCH[1]}"
    echo "${name}.jpg"    # 123_abc_d4e5.jpg
    name="${name}.jpg"    # same thing stored in a variable
else
    echo "$str doesn't match" >&2
fi

# This uses  =~ which is Bash's regex match operator. The results matched
# by (..) are saved to an array called $BASH_REMATCH. The first capture 
# group is stored in index 1, the second (if any) in index 2, Index zero 
# is the full match.

# http://stackoverflow.com/a/1892107/3697757