Check if a command called in a script exists.

cmd_exists.sh

# Reference Commands
cmd_list='usermod groupmod find chgrp getent id awk tr wc'

# Function to check if referenced command exists
cmd_exists() {
  if [ $# -eq 0 ]; then
    echo 'WARNING: No command argument was passed to verify exists'
  fi

  cmd=${1}
  hash "${cmd}" >&/dev/null # portable 'which'
  rc=$?
  if [ "${rc}" != "0" ]; then
    echo "${cmd} command not found" 1>&2
    exit 1
  #else
  #  echo "Found: ${cmd} at ${cmd_fullpath}"
  fi
}

# Verify that referenced commands exist on the system
for cmd in ${cmd_list}; do
  cmd_exists "$cmd"/
done