Perl system call throws strange error - perl

Question

I just wrote a perl script that is restarting a list of services on a linux server. It's intended to run as a cron job. when I execute the script though, I keep getting this error;
root#www:~/scripts# ./ws_restart.pl
* Stopping web server apache2 [ OK ]
sh: Syntax error: "(" unexpected
* Stopping MySQL database server mysqld [ OK ]
sh: Syntax error: "(" unexpected
The call that is being used to do this is;
system("/etc/init.d/apache2 stop");
system("/etc/init.d/mysql stop");
I can paste the entire script code if needed, but I figured that this is the source of the problem and just need to know how to stop it.
Any ideas?
Here's the entire script;
#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;
my $old_pids = {};
my $post_stop_ids = {};
my #services = qw/apache2 mysql solr/;
my $app_dir = '/home/grip/apps/eventfinder';
# collect existing pids then kill services
foreach my $service (#services) {
# gather up existing pids
$old_pids->{$service} = [ get_pids_by_process($service) ];
# issue stop command to each service
set_service_state($service, 'stop');
# attempt to regather same ids
$post_stop_ids->{$service} = [ get_pids_by_process($service) ];
# kill any rogue ids left over
kill_rogue_procs($post_stop_ids->{$service});
# give each kill time to finish
sleep(5);
}
# attempt to restart killed services
foreach my $service (#services) {
# issue start command to each service
set_service_state($service, 'start');
# Let's give each service enough time to crawl outta bed.
# I know how much I hate waking up
sleep(5);
}
# wait for it!...wait for it! :P
# Pad an extra 5 seconds to give solr enough time to come up before we reindex
sleep(5);
# start the reindexing process of solr
system("cd $app_dir ; RAILS_ENV=production rake reindex_active");
# call it a day...phew!
exit 0;
sub kill_rogue_procs {
my #ids = shift;
# check if we still have any rogue processes that failed to die
# if so, kill them now.
if(scalar #ids) {
foreach my $pid (#ids) {
system("kill $pid");
}
}
}
sub set_service_state {
my ($proc, $state) = #_;
if($proc eq 'apache2') {
system("/etc/init.d/apache2 $state");
} elsif($proc eq 'mysql') {
system("/etc/init.d/mysql $state");
} elsif($proc eq 'solr') {
system("cd $app_dir ; RAILS_ENV=production rake sunspot:solr:$state");
}
}
sub get_pids_by_process {
my $proc = shift;
my #proc_ids = ();
open(PSAE, "/bin/ps -ae | grep $proc |") || die("Couldn't run command");
while(<PSAE>) {
push #proc_ids, $_ =~ /(\d{1,5})/;
}
close PSAE;
return #proc_ids;
}

Answer 1

Actually, I'd be more suspicious of what's in #ids in kill_rogue_procs. It's the result of a ps followed by a grep, so might have bogus values if ps doesn't return any results or if the pid isn't 5 digits long.

Answer 2

This is wrong:
sub kill_rogue_procs {
my #ids = shift;
# check if we still have any rogue processes that failed to die
# if so, kill them now.
if(scalar #ids) {
From what you're passing to this sub, #ids will always contain a single array reference, so (scalar #ids) will always be true. It also means you end up passing something like the following to sh:
kill ARRAY(0x91b0768)
You want something like (if the arrayref is empty, there's nothing to loop over anyway):
my $ids = shift;
...
for my $pid (#$ids) {
kill SIGTERM => $pid;
Or instead of the loop:
kill SIGTERM => #$ids;
Also, there is no need to call system to kill a process.
To this, I'd add the last line, so you don't grep the grep process itself:
sub get_pids_by_process {
my $proc = shift;
$proc =~ s/^(.)/[$1]/;

Answer 3

As sh is raising the errors, I'm pretty sure one of the parameters to system is being expanded to something unexpected. I'd print all parameters just prior to passing them to system for a quick debug.