output of system() call

[Madhu Ramachandran]

question.

i am perl newbie. i read that system() call can be used to invoke other
program (shell scripts etc). The return code of the program is returned by
system() call and i have to >> by 8 bits.

is there any variable which will contain ouput printed by the program in
system() call?

eg:
system("mytest.sh");
if mytest.sh has echo "bla" in it. how can i capture the 'bla' value, using
the system() call?

currently iam doing this.
system ("mytest.sh > /tmp/outfile");
# I open this /tmp/outfile and use $line = <outFp>; and get the value.

wondering if there is an easier way to get output.

-Madhu

 

[Joe Smith]

i am perl newbie. i read that system() call can be used to invoke other
program (shell scripts etc)

Where did you read about the system() call? If it was part of any
sort of decent tutorial, it should have told you right there the answer
to your question.

http://perldoc.perl.org/perlfaq8.html

 

[Paul Lalli]

i am perl newbie. i read that system() call can be used to invoke other
program (shell scripts etc). The return code of the program is returned by
system() call and i have to >> by 8 bits.

is there any variable which will contain ouput printed by the program in
system() call?

Read the documentation for the function you're using. It contains the
answer to your question.

perldoc -f system
(3rd paragraph)

Paul Lalli

 

[Tad McClellan]

question.

You put that in there to distinguish from the many posts here
that do not ask a question?

i am perl newbie.

You really should see the Posting Guidelines you know.

i read

Where did you read it?

In the documentation for the software that you are using?

that system() call can be used to invoke other
program

is there any variable which will contain ouput printed by the program in
system() call?

No, but there is a way to capture the output printed by the program
into a variable using something other than the system() function.

how can i capture the 'bla' value, using
the system() call?

You can't.

You'll have to use something other than the system() function.

wondering if there is an easier way to get output.

Yes there is, and it is included in the documentation for the
system() function that you already know about.

Why didn't you read the documentation for the function you are using?


By now you have used up all of your coupons...

So long!

 

[Jürgen Exner]

i am perl newbie. i read that system() call can be used to invoke
other program (shell scripts etc). The return code of the program is
returned by system() call and i have to >> by 8 bits.

is there any variable which will contain ouput printed by the program
in system() call?

Yep. It works exactly as described in paragraph 3, sentence 4 of the
documentation of the very function that you are using.

jue

 

[zentara]

question.

i am perl newbie. i read that system() call can be used to invoke other
program (shell scripts etc). The return code of the program is returned by
system() call and i have to >> by 8 bits.

is there any variable which will contain ouput printed by the program in
system() call?

eg:
system("mytest.sh");
if mytest.sh has echo "bla" in it. how can i capture the 'bla' value, using
the system() call?

currently iam doing this.
system ("mytest.sh > /tmp/outfile");
# I open this /tmp/outfile and use $line = <outFp>; and get the value.

wondering if there is an easier way to get output.

Here is a super simple example using IPC::Open3. Of course,
you don't need the bash, you can run mytest.sh directly.

There are many more techniques around to enhance your use
of IPC::Open3, google for them.
#!/usr/bin/perl
use warnings;
use strict;
use IPC::Open3;
$|=1;

#my $pid=open3(\*IN,\*OUT,\*ERR,'/bin/bash');
my $pid=open3(\*IN,\*OUT,0,'/bin/bash');
# set \*ERR to 0 to send STDERR to STDOUT

my $cmd = 'date';
#send cmd to bash
print IN "$cmd\n"; #need the \n with bash

#getresult
my $result = <OUT>;
print $result;

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