Handling Exceptions on Net::SSH::Expect

pablor has asked for the wisdom of the Perl Monks concerning the following question:

I am using Net::SSH::Expect to connect to a list of access points.

In some cases the connection dies and my script gets interrupted. I want the script to skip the AP but continue with the following ones, but the script dies

my $sshap = Net::SSH::Expect->new (
 host       => $apip,
 user       => 'Cisco', 
 ssh_option => '-o StrictHostKeyChecking=no', 
 raw_pty    => 1,
 timeout     => 5
);

if($sshap->run_ssh()){
    $sshap->waitfor ('Password:', 7) or warn "SSH problem: 'Password' 
+not found after 7 second";
    $sshap->send    ('Cisco');
    $sshap->waitfor ("$ap\>", 3) or warn "SSH problem: $ap\> not found
+ after 3 second";
    $sshap->send    ('en');
    $sshap->waitfor ('Password:', 3) or warn "SSH problem: 'EN Passwor
+d' not found after 3 second";
    $sshap->send    ('Cisco');
    $sshap->waitfor ("$ap\#", 3) or warn "SSH problem: $ap\# not found
+ after 3 second";
    $sshap->send    ('show ip interface brief');
    while (defined ($line = $sshap->read_line()) ) {
        print "$line\n"
    }
    $sshap->send('exit');
    $sshap->close();
        
} else {
    print     "$apname     Could not open SSH\n";
}
[download]

I found that I can handle that by using eval{}

Is that the best approach?

it seems that is running much slower when I use eval.

Comment on Handling Exceptions on Net::SSH::Expect Download Code

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Re: Handling Exceptions on Net::SSH::Expect by kcott (Archbishop) on Jan 16, 2017 at 21:58 UTC
G'day pablor, Welcome to the Monastery. "I found that I can handle that by using eval{} Is that the best approach?" I find Try::Tiny can be a better approach. It's DESCRIPTION starts: "This module provides bare bones try/catch/finally statements that are designed to minimize common mistakes with eval blocks, and NOTHING else." Using eval can have some issues. See the BACKGROUND section of Try::Tiny for a discussion of these issues. As you haven't shown how you're using `eval`, I can't say whether any of those issues apply to you. There's lots of similar modules available, for instance, try CPAN Search for Try::. "it seems* that is running much slower when I use eval."* [my emphasis] Use Benchmark to compare speeds. I recommend running it several times; five is usual for me. — Ken	[reply] [d/l]

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Re: Handling Exceptions on Net::SSH::Expect
by kcott (Archbishop) on Jan 16, 2017 at 21:58 UTC

G'day pablor,

Welcome to the Monastery.

"I found that I can handle that by using eval{} Is that the best approach?"

I find Try::Tiny can be a better approach. It's DESCRIPTION starts:

"This module provides bare bones try/catch/finally statements that are designed to minimize common mistakes with eval blocks, and NOTHING else."

Using eval can have some issues. See the BACKGROUND section of Try::Tiny for a discussion of these issues. As you haven't shown how you're using eval, I can't say whether any of those issues apply to you.

There's lots of similar modules available, for instance, try CPAN Search for Try::.

"it seems that is running much slower when I use eval." [my emphasis]

Use Benchmark to compare speeds. I recommend running it several times; five is usual for me.

— Ken

[reply]
[d/l]