Watch a file or directory for changes and run a command in response. For example: wait_do src/ ./run_tests.py

wait_do.sh

#!/usr/bin/bash

wait_do() {
    if [[ `uname` == 'Darwin' ]]; then
        if ! command -v fswatch &>/dev/null; then
            echo "fswatch not found!"
            return
        fi
        fswatch . ${@}
    else
        if ! command -v inotifywait &>/dev/null; then
            echo "inotifywait not found!"
            return
        fi

        local watch_file=${1}
        shift

        if [[ ! -e ${watch_file} ]]; then
            echo "${watch_file} does not exist!"
            return
        fi

        local exclude_list="(^tags$|\.git|\.pyc$|\.log$|\.yaml$|[[:digit:]])"
        while inotifywait -re close_write --excludei ${exclude_list} ${watch_file} &>/dev/null; do
            local start=$(\date +%s)
            echo "start: $(date)"
            echo "exec:  ${@}"
            ${@}
            local stop=$(\date +%s)
            echo "finished: $(date) ($((${stop} - ${start})) seconds elapsed)"
        done
    fi
}