11.14. Prompt Beeps After Long-Running Commands

#!/usr/bin/perl
require 5.003;
use strict;

###############################################################################
# prompt_bell -- execute arbitrary commands contingent upon CPU time
#
# Copyright (C) 2000 Robb Matzke
#
#    This program is free software; you can redistribute it and/or modify it
#    under the terms of the GNU General Public License as published by the
#    Free Software Foundation; either version 2 of the License, or (at your
#    option) any later version.
#
#    This program is distributed in the hope that it will be useful, but
#    WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
#    Public License for more details.
#
#    You should have received a copy of the GNU General Public License along
#    with this program; see the file COPYING.  If not, write to the Free
#    Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
#    02111-1307, USA.
#
# Purpose:
#
#    This program is intended to be called each time a shell prompt is
#    displayed. It looks at current CPU times (user+system) for the shell and
#    its children, and if the CPU time is more than some user-specified amount
#    then user-specified commands are executed.  The author uses it to provide
#    an audio indication of when a long-running command completes.
#
# Usage:
#
#    The prompt_bell command takes two arguments: the name of a file
#    containing the latest CPU usage information for the shell and its
#    children, and some optional state information from the environment
#    variable $PROMPT_BELL_STATE.
#
#    The times file simply contains one or more times, zero or more to a line,
#    each of the form `#h#m#.#s' where `#' is a sequence of one or more
#    decimal digits and `#h' is the optional number of hours, `#m' is the
#    required number of minutes, and `#.#s' is the number of seconds and
#    fractions thereof. The total time is the sum of all the times in this
#    file. Example:
#
#        0m0.050s 0m0.060s
#        0m15.790s 0m0.220s
#
#    The output from this command is one or more semicolon-separated shell
#    commands which should be eval'd by the caller. If the difference between
#    the current CPU times and the previous CPU times (stored in environment
#    variable PROMPT_BELL_STATE) is more than $PROMPT_BELL_TIME seconds
#    (default 10) then the commands printed include the value of environment
#    variable PROMPT_BELL_CMD (default is "echo -ne '\a'").
#
#    Typical usage is:
#        eval "`prompt_bell $TIMES_FILE $PROMPT_BELL_STATE`"
#
#    and this command is usually part of the bash PROMPT_COMMAND. The author's
#    .bashrc contains the following:
#
#        PROMPT_BELL_TIME=15
#        PROMPT_BELL_CMD="echo -e 'done.\a'"
#
#        COMMAND_PROMPT='TIMES_FILE=/tmp/times.$$;
#                        times >$TIMES_FILE;
#                        eval "`prompt_bell $TIMES_FILE $PROMPT_BELL_STATE`";
#                        /bin/rm -f $TIMES_FILE'
#        export PROMPT_BELL_TIME PROMPT_BELL_CMD COMMAND_PROMPT
#
#    Note: the output of `times' is stored in a temporary file to prevent it
#    from being executed in a subshell whose CPU times are always nearly zero.
#
##############################################################################

# Convert #h#m#s to seconds.
sub seconds {
  my($hms) = @_;
  my($h,$m,$s) = $hms =~ /^(?:(\d+)h)?(\d+)m(\d+\.\d+)s/;
  return $h*3600 + $m*60 + $s;
}

# Obtain processor times in seconds
my $times_file = shift;
my $ptime_cur = 0;
open TIMES_FILE, $times_file or die "prompt_bell: $times_file: $!\n";
while (<TIMES_FILE>) {
  s/(?:(\d+)h)?(\d+)m(\d+(?:\.\d+)?)s/$ptime_cur+=$1*3600+$2*60+$3/eg;
}
close TIMES_FILE;


# Obtain previous state to compute deltas.
my $ptime_prev = shift;

# If the processor time was more than $PROMPT_BELL_TIME or 10 seconds
# then beep.
my $beep;
my $limit = exists $ENV{PROMPT_BELL_TIME}?$ENV{PROMPT_BELL_TIME}:10;
if ($ptime_cur-$ptime_prev>$limit) {
  $beep = ";" . ($ENV{PROMPT_BELL_CMD} || "echo -ne '\\a'");
}

# Generate the shell commands
print "PROMPT_BELL_STATE=$ptime_cur$beep\n";
exit 0;