useful_shell

string_contains.sh

# contains(string, substring)
#
# Returns 0 if the specified string contains the specified substring,
# otherwise returns 1.
# https://stackoverflow.com/questions/2829613/how-do-you-tell-if-a-string-contains-another-string-in-unix-shell-scripting
contains() {
    string="$1"
    substring="$2"
    if test "${string#*$substring}" != "$string"
    then
        return 0    # $substring is in $string
    else
        return 1    # $substring is not in $string
    fi
}

ANY_CHANGES=$(git commit -m "Any changes?")
contains "$ANY_CHANGES" "nothing to commit" && echo "Yes"
contains "$ANY_CHANGES" "nothing to commit" || echo "No"