Executing unix commands from a Perl file

[carlosAlberto]

Hello,

I would like to execute the following unix command from my Perl file:

snmpwalk -v 3 -u testUser -l noAuthNoPriv $ipAddress $miboid

and then display the result to the screen.

How is is possible to execute this command and display the result???????????????

All help greatly appreciated.


Regards,
Carl.

 

[MikeLacey]

a couple of different ways

easy:

$a = `your_command`;
print $a;

but not what you'd call flexible....

a bit harder:

open(CMD, "your_command|"
while(<CMD>){
print $_;
}

that way you can control how many lines you dislay, edit the content and format of the lines etc Mike

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[marblecat]

system(&quot;your_command&quot;

 

[carlosAlberto]

Hi,

I've took the above command a little further but have come up with another error i can't solve.

PROBLEM:
open(RESULTS, &quot;$snmpCommand -v 3 -u testUser -l noAuthNoPriv $ipAddress $miboid | &quot;


The command works when it begins without a variable:
open(RESULTS, &quot;snmpwalk -v 3 -u testUser -l noAuthNoPriv $ipAddress $miboid | &quot;


I have checked to make sure $snmpCommand contains the value 'snmpwalk' but i still get an error.


I am soooo puzzled.... please help!!

Carl.

 

[carlosAlberto]

oh

I define the variable as follows, just in case


my ($snmpCommand) = snmpwalk;

 

[MikeLacey]

Should, I think, be:

my ($snmpCommand) = 'snmpwalk'; Mike

Want to get great answers to your Tek-Tips questions? Have a look at faq219-2884

It's like this; even samurai have teddy bears, and even teddy bears get drunk.

 

[carlosAlberto]

Hi Mike,

Thanks for the reply.

I tried that and that doesn't seem to work.

I also tried creating a variable as:


my $command = '$snmpCommand -v 3 -u testUser -l noAuthNoPriv $ipAddress $miboid | ';

open (RESULTS, $command);


which also didn't work.

????

Carl.

 

[rosenk]

[tt]my $command = '$snmpCommand ...'[/tt]
wouldn't work. Variables don't expand in single quotes.

Try double quotes.

 

[carlosAlberto]

Hi,

I tried the previous comment with no success. Here are my commands:

my $snmpCommand = 'snmpwalk -v 3 -Os -u $userName -a MD5 -A $authPass -l authPriv -x DES -X $privPass $ipAddress $miboid |';

open (RESULTS, $snmpCommand)

 

[rosenk]

Was that a typo, or still using single quotes? Your assignment should be:

[tt]my $snmpCommand = &quot;snmpwalk -v 3 -Os -u $userName -a MD5 -A $authPass -l authPriv -x DES -X $privPass $ipAddress $miboid |&quot;;[/tt]

 

[icrf]

what rosenk is saying:

my $var1 = "Perl";
my $var2 = '$var1';
my $var3 = "$var1";

print "$var1\n$var2\n$var3\n";

outputs

Perl
$var1
Perl

When variables are within single quotes, they aren't interpolated (expanded out to their value), but within double quotes, they are. ----------------------------------------------------------------------------------
...but I'm just a C man trying to see the light

 

[carlosAlberto]

yes sorry, I've actually tried both ways.

I'll just include the lines i'm having problems with again:

my $snmpCommand = &quot;snmpwalk -v 3 -Os -u $userName -a MD5 -A $authPass -l authPriv -x DES -X $privPass $ipAddress $miboid |&quot;;

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Executing unix commands from a Perl file
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carlosAlberto (IS/IT--Manageme) Jan 22, 2003
Hello,

I would like to execute the following unix command from my Perl file:

snmpwalk -v 3 -u testUser -l noAuthNoPriv $ipAddress $miboid

and then display the result to the screen.

How is is possible to execute this command and display the result???????????????

All help greatly appreciated.


Regards,
Carl.





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MikeLacey (MIS) Jan 22, 2003
a couple of different ways

easy:

$a = `your_command`;
print $a;

but not what you'd call flexible....

a bit harder:

open(CMD, &quot;your_command|&quot;
while(<CMD>){
print $_;
}

that way you can control how many lines you dislay, edit the content and format of the lines etc
Mike

Want to get great answers to your Tek-Tips questions? Have a look at FAQ219-2884

It's like this; even samurai have teddy bears, and even teddy bears get drunk.




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marblecat (Programmer) Jan 23, 2003
system(&quot;your_command&quot;


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carlosAlberto (IS/IT--Manageme) Jan 29, 2003
Hi,

I've took the above command a little further but have come up with another error i can't solve.

PROBLEM:
open(RESULTS, &quot;$snmpCommand -v 3 -u testUser -l noAuthNoPriv $ipAddress $miboid | &quot;


The command works when it begins without a variable:
open(RESULTS, &quot;snmpwalk -v 3 -u testUser -l noAuthNoPriv $ipAddress $miboid | &quot;


I have checked to make sure $snmpCommand contains the value 'snmpwalk' but i still get an error.


I am soooo puzzled.... please help!!

Carl.






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area for this forum!



carlosAlberto (IS/IT--Manageme) Jan 29, 2003
oh

I define the variable as follows, just in case


my ($snmpCommand) = snmpwalk;





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MikeLacey (MIS) Jan 29, 2003
Should, I think, be:

my ($snmpCommand) = 'snmpwalk';
Mike

Want to get great answers to your Tek-Tips questions? Have a look at FAQ219-2884

It's like this; even samurai have teddy bears, and even teddy bears get drunk.




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carlosAlberto (IS/IT--Manageme) Jan 29, 2003
Hi Mike,

Thanks for the reply.

I tried that and that doesn't seem to work.

I also tried creating a variable as:


my $command = '$snmpCommand -v 3 -u testUser -l noAuthNoPriv $ipAddress $miboid | ';

open (RESULTS, $command);


which also didn't work.

????

Carl.





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rosenk (Programmer) Jan 29, 2003
my $command = '$snmpCommand ...'
wouldn't work. Variables don't expand in single quotes.

Try double quotes.


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carlosAlberto (IS/IT--Manageme) Jan 29, 2003
Hi,

I tried the previous comment with no success. Here are my commands:

my $snmpCommand = &quot;snmpwalk -v 3 -Os -u $userName -a MD5 -A $authPass -l authPriv -x DES -X $privPass $ipAddress $miboid |&quot;;

open (RESULTS, $snmpCommand);

@replyData = <RESULTS>;


To which @replyData is empty.


The following command did work:
open (RESULTS, &quot;snmpwalk -v 3 -Os -u $userName -a MD5 -A $authPass -l authPriv -x DES -X $privPass $ipAddress $miboid |&quot;;

But to bring flexibility there is more than 1 type of snmp command.

Thanks for your help.

Carl.

 

[carlosAlberto]

ooooops, not sure what happened there....



yes sorry, I've actually tried both ways.

I'll just include the lines i'm having problems with again:

my $snmpCommand = &quot;snmpwalk -v 3 -Os -u $userName -a MD5 -A $authPass -l authPriv -x DES -X $privPass $ipAddress $miboid |&quot;;

open (RESULTS, $snmpCommand);

@replyData = <RESULTS>;


To which @replyData is empty.


The following command did work:
open (RESULTS, &quot;snmpwalk -v 3 -Os -u $userName -a MD5 -A $authPass -l authPriv -x DES -X $privPass $ipAddress $miboid |&quot;;

But to bring flexibility there is more than 1 type of snmp command.

Thanks for your help.

Carl.

 

[rosenk]

Very strange. This test works perfectly fine for me:
[tt]my $command = &quot;ls |&quot;;
open(RESULTS, &quot;$command&quot;
print while (<RESULTS>);[/tt]

I don't think it will help me know why it's not working, but what version of perl are you using and under what OS?

 

[carlosAlberto]

Perl v5.6.1

Redhat 7.3

 

[justice41]

This may seem obvious, but is the assignment to $snmpCommand

my $snmpCommand = "snmpwalk -v 3 -Os -u $userName -a MD5 -A $authPass -l authPriv -x DES -X $privPass $ipAddress $miboid |";

being made after the other variables ($userName, $authPass, etc.) have valid values assigned to them?

Also, are you running this with warnings and strict turned on? (i.e. [tt]use warnings; use strict;[/tt])

jaa

 

[carlosAlberto]

Jaa,

Yep, the other variables are assigned first.

I don't have any warning declarations... Is there 1 of the 2 i should be using do you think????


Thanks.

Carl.

 

[carlosAlberto]

I'm actually 'printing' the $snmpCommand variable which is exactly correct. I have copied it straight to the command line and ran fine.

But for some reason the open () is dieing.......


Carl.

 

[carlosAlberto]

I have the following piece of code to assigned the $snmpCommand variable.



if ($miboid =~ /Table$/) {
my $snmpCommand = &quot;snmptable -v 3 -Os -u $userName -a MD5 -A $authPass -l authPriv -x DES -X $privPass -CB $ipAddress $miboid |&quot;;
}
else {
my $snmpCommand = &quot;snmpwalk -v 3 -Os -u $userName -a MD5 -A $authPass -l authPriv -x DES -X $privPass $ipAddress $miboid |&quot;;
print &quot;$snmpCommand&quot;;
}

print &quot;$snmpCommand&quot;;


The print $snmpCommand works fine within the else, but once out of the loop displays nothing. Is something to do with the 'my'. I used this as i wanted it to be local to this subroutine.


This my help to solve the problem.

Thanks.

Carl.

 

[justice41]

Yes, the my() localizes $snmpCommand to the if block. You need to declare it in the closing scope of the subroutine block instead.

sub mysub {
   my $snmpCommand; 
   ...
   if ($miboid =~ /Table$/) {
      $snmpCommand = " .. ";
   }
   else {
      $snmpCommand = " .. ";
   }
}

jaa