Controling and interactive program

[jblapham]

Has anyone ever written a perl script to control and interactive program. One that prompts for input. I want to call the program, wait for the prompt, send it the input, and capture the return code. I'm not sure how to do this. Any examples are welcome.

[Paladin]

If this is a command line program you want to control, try the Expect module.

[perrin]

Yeah, either Expect or IPC::Run should do it.

[etcshadow]

IPC::Run... specifically, read the section on pump.

[johnnywang]

Another set of CPAN modules for commandline purposes are Shell::Base and Term::ReadLine

[zentara]

Here is an example using 'bc' the calculator. It uses IPC::Open3. (There are pitfalls to watch out for with IPC, like when you try to get huge output thru the buffered pipes....but you will know it if you hit that problem :-) )

#!/usr/bin/perl
use warnings;
use strict;
use IPC::Open3;
use IO::Select;

#interface to "bc" calculator 
my $pid = open3(\*WRITE, \*READ,\*ERROR,"bc");
            #if \*ERROR is false, STDERR is sent to STDOUT  

my $selread = new IO::Select();
my $selerror = new IO::Select();
$selread->add(\*READ);
$selerror->add(\*ERROR);
# may not be best use of IO::Select, but it works :-) 

my($error,$answer)=('','');

while(1){

print "Enter expression for bc, i.e. 2 + 2\n";
chomp(my $query = <STDIN>);

#send query to bc 
print WRITE "$query\n";

#timing delay needed tp let bc output 
select(undef,undef,undef,.01);

#see which filehandles have output 
if($selread->can_read(0)){print "ready->read\n"}
if($selerror->can_read(0)){print "ready->error\n"}

#get any error from bc 
sysread(ERROR,$error,4096) if $selerror->can_read(0);
if($error){print "\e[1;31m ERROR-> $error \e[0m \n"}

#get the answer from bc 
sysread(READ,$answer,4096) if $selread->can_read(0);
if($answer){print "$query = $answer\n"}

($error,$answer)=('','');
}

waitpid($pid, 1);
# It is important to waitpid on your child process,   
# otherwise zombies could be created.