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

First off - I would say I am intermediate PERL programmer. I can follow instruction, examples, etc. I wrote a program to ssh2 into a server and return some data. I've posted code that works vs code that doesn't work. Here's the problem... If i put something like 'ls -la /directory/cirectory2' within the parens on the exec line it works ok. However my zcat command with the grep statement doesn't work :/ The $ibmslapd_fn variable is poulated and is a string format. I've also tried it with & without the dbl quotes and would really like to know what I'm doing wrong so I can get the zcat cmd to work too! Thanks in advance for your time and knowledge.

THIS WORKS FINE
my $chan = $ssh2->channel();
$chan->blocking(0);
$chan->exec('ls -la /db2home/idsldap/idsslapd-idsldap/logs/');
while (<$chan>){ print FILE }
print FILE "\n\n\n\n";
$ssh2->disconnect(); ### DISCONNECT ###

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THIS DOESN'T WORK 
my $chan = $ssh2->channel();
$chan->blocking(0);
$chan->exec('zcat /db2home/idsldap/idsslapd-idsldap/logs/ibmslapd.log.
+$ibmslapd_fn-2350.gz | grep -i "entries have been successfully" ');
while (<$chan>){ print FILE }
print FILE "\n\n\n\n";
$ssh2->disconnect(); ### DISCONNECT ###

[download]


Replies are listed 'Best First'.
Re: NET:SSH2 exec syntax usage
by Illuminatus (Curate) on Apr 15, 2011 at 22:20 UTC
    1. Your zcat command is encased in single-quotes, which means that variable substitution will not occur.
    2. It is not totally clear from the documentation, but I am pretty sure that setting blocking to 0 means non-blocking. Since the ls probably returns right away, this makes no difference in the first case. zcat, however, can take a while on files of non-trivial size. Since you are not checking for EAGAIN, this could give you a problem

    fnord

[reply]

      Illuminatus is correct. If you want to use single quotes, you will have to concatenate your variables. Otherwise you can switch them to double quotes and backslash your literal double-quotes.

      ex. $chan->exec('zcat /db2home/idsldap/idsslapd-idsldap/logs/ibmslapd.log.' . $ibmslapd_fn . '-2350.gz | grep -i "entries have been successfully" ');

      or

      ex. $chan->exec("zcat /db2home/idsldap/idsslapd-idsldap/logs/ibmslapd.log.$ibmslapd_fn-2350.gz | grep -i \"entries have been successfully\" ");

[reply]
        Thank You SitrucHtims.

        This Worked
        ex. $chan->exec('zcat /db2home/idsldap/idsslapd-idsldap/logs/ibmslapd.log.' . $ibmslapd_fn . '-2350.gz | grep -i "entries have been successfully" ');

        This Didn't
        escaping the double quotes didn't work...
        $chan->exec("zcat /db2home/idsldap/idsslapd-idsldap/logs/ibmslapd.log.$ibmslapd_fn-2350.gz | grep -i \"entries have been successfully\" ");

        Thanks again for your assistance. My Issue is solved.

        The $chan->blocking(0); statement didn't seem to matter.
[reply]

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