A shell function that executes a command and tells if it succeeded or failed with customizable output.

okko.sh

#$ okko [opts] message command [args]*
#
#  This shell function provides a way to run a command and present its result
#  in a user-friendly way.
#
#  The provided message is initially printed to the screen, then the command is
#  run with the given arguments. After command completion, 'ok' is printed if
#  the command exited with a tatus of 0, else 'err(N)' is printed, where N is
#  the error code.
#
#  Everything output by this command can be overriden using environment
#  variables as follows:
#    OKKO_MESSAGE  The message format as a printf string. The user-specified
#                  mesage is passed as the first argument, and should be
#                  specified as %b to allow escapes.
#    OKKO_SUCCESS  The printf format for a successful command. No arguments are
#                  passed to printf.
#    OKKO_FAILURE  The printf format for a failed command. The error code is
#                  passed as the first argument.
#
#  At any time, set these variables to an empty string to return to the default
#  formats. Be aware that everything is output using printf, which makes you
#  explicitly write the final newline character.
#
#  The exit status of this function is set to the exit status of the command, so
#  you may give more useful information of what failed, if available.
okko() {
  [ -z "$OKKO_MESSAGE" ] && OKKO_MESSAGE="%b "
  [ -z "$OKKO_SUCCESS" ] && OKKO_SUCCESS="ok\n"
  [ -z "$OKKO_FAILURE" ] && OKKO_FAILURE="err(%d)\n"

  printf "$OKKO_MESSAGE" "$1"
  shift

  "$@"; local E="$?"

  [ "$E" -eq "0" ] \
    && printf "$OKKO_SUCCESS" \
    || printf "$OKKO_FAILURE" "$E"

  return "$E"
}