Sequence 2 commands behind a lock

sequenced.sh

#!/usr/bin/env bash
#  Locking from: https://gist.github.com/jpclipffel/0b8f470be029fc9e3f07 

#  Run two bash commands in sequence using flock to prevent
#  from running multiple instances in paralell
#  ./sequenced.sh -g echo 'Hello' > test.txt -t cat test.txt -n lock_name

while getopts 1:2:n: flag; do
  case "${flag}" in
  1) FIRST_CMD=${OPTARG} ;;
  2) SECOND_CMD=${OPTARG} ;;
  n) LOCK_FILE=${OPTARG} ;;
  esac
done

function first(){
   eval "${FIRST_CMD}"
   return 0
}

function second(){
   eval "${SECOND_CMD}"
   return 0
}

# Lock timeout in seconds -- 86400 seconds == 1 day
TIMEOUT=86400

# Create the lockfile.
touch $LOCK_FILE

# Create a file descriptor over the given lockfile.
exec {FD}<>$LOCK_FILE

# Try to lock the file descriptor $FD during $TIMEOUT seconds.
# If it failsm exit with an error.
# Otherwise, the lock is acquired and implicitely droped at the end of the script.
if ! flock -x -w $TIMEOUT $FD; then
  echo "Failed to obtain a lock within $TIMEOUT seconds"
  echo "Another instance of sequenced.sh is probably running against the same lock file."
  exit 1
else
  echo "Lock acquired running sequenced commands"
  first && second
fi