error handling telnetting to hosts in CSV file

[matcor9925]

Hello,

I'm using the Net::Telnet::Cisco module to update configs on multiple Cisco routers (all are 1841 model). The script reads from a CSV file that has the router IP, and commands to be entered. The script runs fine unless a router does not respond to telnet in which case the script does not continue to execute. I need some help implementing error handling so the script will skip an unresponsive host and write the unresponsive host to a file, then continue to the next host in the CSV file. Also, after a reload command is entered for a particular router, the script does not continue to execute. Any help would be greatly appreciated.

Example of my perl script:

<SNIP>
#!/usr/bin/perl
#

use Net::Telnet::Cisco;

#Username for router
print "Enter username\n";
$user = <STDIN>;
chomp($user);

#password for router
print "Enter password\n";
$pass = <STDIN>;
chomp($pass);

#CSV file with router IP and commands
print "Enter filename\n";
$State = <STDIN>;
chomp($State);

open (INDB, "./$State.csv") or
die "cannot find file";

#reads every line in CSV file
while (<INDB>)
{
$SiteData = $_;
chomp ($SiteData);
($HostNumber, $loopback, $copytftpst, $tftpserver, $configpath, $deststcfg, $reload) =

split (/,/, $SiteData);

my $CISCO_IP = "$loopback";
my $username = "$user";
my $password = "$pass";
my $enable_password = "$pass";

my $session = Net::Telnet::Cisco->new(Host => $CISCO_IP, Input_log=> "$SiteNumber.txt", Timeout=> '120');

$session->login($username, $password);

my @output = "";
my @host = "";

# Enable mode
if ($session->enable($enable_password) )
{
@output = $session->cmd('show privilege');
@host = $session->cmd('sho run | include hostname');
print "@output for @host $loopback\n";
}
else
{
warn "Can't enable: " . $session->errmsg;
}

$session->cmd("$copytftpst\n$tftpserver\n$configpath\n$deststcfg\n$reload");
$session->close;

}
<SNIP>

Example of CSV file with hosts/commands:

<SNIP>
rtr1, 10.1.1.1, copy tftp startup-config, 10.0.0.1, rtr1/rtr1.1800.txt, startup-config, reload
rtr2, 10.2.2.2, copy tftp startup-config, 10.0.0.1, rtr2/rtr2.1800.txt, startup-config, reload
<SNIP>

Thank you,

Matt

 

[Kirsle]

Try alarms.

# most of your code

# a lexical block
eval {
   # set the alarm
   $SIG{ALRM} = sub { die; }
   alarm(30);

   # do something that is potentially time-consuming
   sleep(int(rand(100)));

   # if it passed, unset the alarm and continue
   alarm(0);
   print "the sleep survived!\n";
};
if ($@) {
   # $@ probably equals "Alarm clock."
   print "the alarm clock went off!\n";
}

you can set $SIG{ALRM} to whatever you want. The "die" there doesn't kill your entire script because the code was wrapped inside an eval, so it only kills the eval and sets $@ to be the text of the error (you could have the die say something else and $@ would equal that text).

I haven't tested alarms on Windows systems. If it doesn't work you can use threads.

use threads;
use threads::shared;

my $success : shared;
$success = 0;

my $thr = threads->create (sub {
   # set up a thread kill handler
   $SIG{KILL} = sub { threads->exit(); };
   # do your time-consuming stuff here

   # set $success = 1 when the thread looks
   # like it'll be okay
   $success = 1;
});

# execution immediately continues here
# at the same time the thread is executing
sleep 30;
if ($success == 0) {
   # the thread isn't survivng
   $thr->kill ('KILL')->detach();
}

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