Service controller for Linux/Unix

[jjhorner]

Category:

System Admin

Description:

Pretty simple script to start and stop services without having to type in paths.

Revisions are welcome and encouraged.

#!/usr/bin/perl 
#
#       Author: J. J. Horner
#       Date: 02/08/2001
#
#  Script to start and stop services without having to type in paths
#  Infinitely lazy way to do things, but it works.
#  script should be in a directory in root's path and executable
#  link 'ln -s /usr/sbin/start /usr/sbin/stop'
#
#  Paths may need to be reset.

use strict;

my $service = shift;
$0 =~ /([^\/]+)$/;
my $action = $1;
$service =~ tr~/~~d;

if (-e "/etc/rc.d/init.d/$service") {
        exec("/etc/rc.d/init.d/$service", $action) or die "exec: $!";
} else {
        print("Service $service does not exist on this system.\n");
}

[Fastolfe]

We use scripts like this for some other service-type applications on our system (though not necessarily via /etc/rc.d) a LOT. A lot of applications make the assumption that one or two instances of a given application will be installed, so they give you one 'admin' script for each instance and you issue a set of start/stop/status type commands to run it. Since we have dozens of instances running, this can be painful, so like you, we've set up scripts that reverse the order of the action. Instead of telling instance X to start, we "start" instance X.

I might suggest the following changes:

my $service = shift;
my ($action) = $0 =~ m![^/]+)$!;   # corrected per reply

$service =~ tr~/~~d;

die "$service: No such service" unless -x "/etc/rc.d/init.d/$service" 
+&& -f _;
exec("/etc/rc.d/init.d/$service", $action) or die "exec: $!";

By using the multi-argument form of exec (or system for that matter), we don't have to worry about shell metacharacters mucking us up. This is probably reasonably safe to run set-uid or via sudo.

[jjhorner]

In

my $action = $0 =~ /([^/]+)$/;

You need to escape your forward slash, and in this format, $action is given a true value ('1'), but is not given the result of the match.

The following works and is added to the code:

$0 =~ /([^\/]+)$/;
my $action = $1;

Thanks for your comments.

J. J. Horner
Linux, Perl, Apache, Stronghold, Unix
[e-mail] http://www.knoxlug.org/

[Fastolfe]

You're right; I had intended to write something more like this:

my ($action) = $0 =~ m!([^/]+)$!;

Either way, you figured it out. I usually prefer the one-line form like this, because with the two-line form, if the regex fails, an assignment to $1 might get you something you do not expect (the results from a previous regex, for example).

[tadman]

Though at the risk of the dreaded featuritis, why not extend this little script to operate in 'suid' mode (with taint checking, of course) so that regular users can do stuff without 'sudo' or 'su' such as restart the Apache server or DNS?

A little 'chmod +s', checking of $< and it might be that exponentially more useful. Of course, 'suid' mode could be an option, such that it doesn't explicitly have to be suid, but if it were, you can be even more lazy.