mv-in-place a file, keep it under the same directory - change just the basename

mvip

#!/usr/bin/env bash

# Change the name of a file without having to specify its full path from
# scratch. Instead specify only the modified filename, and keep it under the
# same parent directory.

name=$(basename $0)
args=$@

function usage() {
    echo -e "Usage:\n\n$name <path-to-file>    <new-filename-in-same-dir>"
    echo    "$name <path-to-file> -p <new prefix>"
    echo    "$name <path-to-file> -s <new suffix>"
}

function bad() {
    usage
    exit 1
}

if [[ $# != 2 && $# != 3 ]]; then
    bad
fi

filename=$1
shift

while test $# -gt 0; do
    case "$1" in
        -h|--help)
            usage
            exit 0
            ;;
        -p)
            shift
            if [[ $# -eq 1 ]]; then
                prefix="$1"
                mv $filename $(dirname $filename)/$prefix$(basename $filename)
                exit 0
            else
                bad
            fi
            exit 0
            ;;
        -s)
            shift
            if [[ $# -eq 1 ]]; then
                suffix="$1"
                mv $filename $filename$suffix
                exit 0
            else
                bad
            fi
            exit 0
            ;;
        *)
            new_name=$1
            mv $filename $(dirname $filename)/$new_name
            break
            ;;
    esac
done