watch-exec

#!/usr/bin/env bash

# AUTHOR: Zander : zander@xargs.io : @_ZPH
# LICENSE: MIT
# Credit for initial script: http://stackoverflow.com/a/18341108/1930671

set -o nounset
set -o pipefail
set -o errexit
# set -o xtrace

set -x

readonly PROGNAME=$(basename $0)

readonly ARGS="$@"
readonly TO_MONITOR="$1";shift
readonly CMD_TO_RUN="$*"
readonly PID="$$"

PRIOR_ATIME="0"

set +x

run_loop(){
  while true

  do

    ATIME=`stat -f %Z ${TO_MONITOR}`

    if ! [[ $ATIME == $PRIOR_ATIME ]];then

      echo "CMD: ${CMD_TO_RUN}"
      $(${CMD_TO_RUN})
      PRIOR_ATIME=$ATIME
    fi
    sleep 1

  done
}

usage(){
  echo "$PROGNAME [file-to-watch] [*cmd-to-run]"
  exit 1
}

main(){

  if [[ $# -lt 2 ]];then
    usage
  fi

  if [[ $CMD_TO_RUN == "" ]];then
    echo "No cmd to execute"
    exit 1
  fi

  run_loop
}

main $ARGS