[Scripts/git/.git] / crondiff / crondiff.pl

#!/usr/bin/env perl
use strict;
use warnings;
use Digest::MD5 qw(md5_hex);

=head1 NAME

crondiff.pl - Run command periodically and compare their output.

=head1 DESCRIPTION

crondiff.pl is designed to be run from cron periodically. It takes as
input a list of commands to run. Each time it is invoked, it runs the
commands listed, and sends mail to the user running the script if the
output of that command has changed since the last run.

=head1 USAGE

=over 4

=item

Create a file C<~/.crondiff/cmdlist>, containing one line per file, of
commands to be checked.

=item

Add C<crondiff.pl> to your crontab. The following example runs it
directly out of the locker (not necessarily a good idea!) every hour:

    # m h  dom mon dow   command
      0 *  *   *   * PATH=/bin:/usr/bin: perl /mit/snippets/crondiff/crondiff.pl

=back

=head1 ASSUMPTIONS

=over 4

=item

Mail goes to C<$USER@mit.edu>, for the user who runs this script.

=item

Mail will be sent using C<mutt -x>.

=back

If you don't like these assumptions, patches are welcome :)

=cut

my $confdir = $ENV{HOME} . "/.crondiff";
unless($ENV{USER}) {
    chomp(my $user = `id -un`);
    $ENV{USER} = $user;
};
my $mailto = $ENV{USER} . '@mit.edu';
my @mailer = qw(mutt -x);

my $cachedir = "$confdir/cache";

mkdir("$cachedir") unless -e "$cachedir";

open(my $clist, "<", "$confdir/cmdlist")
  or exit;

while(my $cmd = <$clist>) {
    chomp($cmd);
    my $hash = md5_hex($cmd);
    my $pid = fork;
    if($pid == 0) {
        # Child
        close(STDOUT);
        close(STDERR);
        open(STDOUT, ">>", "$cachedir/$hash.new");
        open(STDERR, ">>", "$cachedir/$hash.new");
        exec($cmd);
    }
    waitpid($pid, 0);
    if($? != 0) {
        # Exited with error, should send mail, but punting for now.
        unlink("$cachedir/$hash.new");
        next;
    } elsif(-f "$cachedir/$hash"
       && system("diff -q $cachedir/$hash.new $cachedir/$hash > /dev/null 2>&1") != 0) {
        # Output changed
        if(($pid = fork) == 0) {
            close(STDOUT);
            open(STDOUT, "|-", @mailer, $mailto, '-s', "Output of [$cmd]");
            system("date");
            print "----\n";
            system("diff", "-u", "-U", "0", "$cachedir/$hash", "$cachedir/$hash.new");
            exit;
        } else {
            waitpid($pid, 0);
        }
    }
    rename("$cachedir/$hash.new", "$cachedir/$hash");
}
Commit	Line	Data
b0e0b6e8 NE	1	#!/usr/bin/env perl
	2	use strict;
	3	use warnings;
	4	use Digest::MD5 qw(md5_hex);
	5
	6	=head1 NAME
	7
	8	crondiff.pl - Run command periodically and compare their output.
	9
	10	=head1 DESCRIPTION
	11
	12	crondiff.pl is designed to be run from cron periodically. It takes as
	13	input a list of commands to run. Each time it is invoked, it runs the
	14	commands listed, and sends mail to the user running the script if the
	15	output of that command has changed since the last run.
	16
	17	=head1 USAGE
	18
	19	=over 4
	20
	21	=item
	22
	23	Create a file C<~/.crondiff/cmdlist>, containing one line per file, of
	24	commands to be checked.
	25
	26	=item
	27
	28	Add C<crondiff.pl> to your crontab. The following example runs it
	29	directly out of the locker (not necessarily a good idea!) every hour:
	30
	31	# m h dom mon dow command
	32	0 * * * * PATH=/bin:/usr/bin: perl /mit/snippets/crondiff/crondiff.pl
	33
	34	=back
	35
	36	=head1 ASSUMPTIONS
	37
	38	=over 4
	39
	40	=item
	41
	42	Mail goes to C<$USER@mit.edu>, for the user who runs this script.
	43
	44	=item
	45
	46	Mail will be sent using C<mutt -x>.
	47
	48	=back
	49
	50	If you don't like these assumptions, patches are welcome :)
	51
	52	=cut
	53
	54	my $confdir = $ENV{HOME} . "/.crondiff";
	55	unless($ENV{USER}) {
	56	chomp(my $user = `id -un`);
	57	$ENV{USER} = $user;
	58	};
	59	my $mailto = $ENV{USER} . '@mit.edu';
	60	my @mailer = qw(mutt -x);
	61
	62	my $cachedir = "$confdir/cache";
	63
	64	mkdir("$cachedir") unless -e "$cachedir";
65
66	open(my $clist, "<", "$confdir/cmdlist")
67	or exit;
68
69	while(my $cmd = <$clist>) {
70	chomp($cmd);
71	my $hash = md5_hex($cmd);
72	my $pid = fork;
73	if($pid == 0) {
74	# Child
75	close(STDOUT);
76	close(STDERR);
77	open(STDOUT, ">>", "$cachedir/$hash.new");
78	open(STDERR, ">>", "$cachedir/$hash.new");
79	exec($cmd);
80	}
81	waitpid($pid, 0);
82	if($? != 0) {
83	# Exited with error, should send mail, but punting for now.
84	unlink("$cachedir/$hash.new");
85	next;
86	} elsif(-f "$cachedir/$hash"
87	&& system("diff -q $cachedir/$hash.new $cachedir/$hash > /dev/null 2>&1") != 0) {
88	# Output changed
89	if(($pid = fork) == 0) {
90	close(STDOUT);
91	open(STDOUT, "\|-", @mailer, $mailto, '-s', "Output of [$cmd]");
92	system("date");
93	print "----\n";
94	system("diff", "-u", "-U", "0", "$cachedir/$hash", "$cachedir/$hash.new");
95	exit;
96	} else {
97	waitpid($pid, 0);
98	}
99	}
100	rename("$cachedir/$hash.new", "$cachedir/$hash");
101	}