Says galande:
> if I am giving a wrong command I am getting error.
> But, from then onwards I am not getting output of
> even correct command. what could be wrong ??
You have: 
    my $cmd = <STDIN>;
    print Writer $cmd;
    my $got = <Reader>;
    print $got;

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Suppose $cmd is a bad command. You send it to the shell. Then you try to read from Reader. This waits for the shell to print a line on its stdout. But when $cmd is bad, the shell prints nothing on stdout. Instead, it prints an error message on its stderr. The line my $got = <Reader>; waits for stdout from the shell, but there is none. It waits forever.

This is exactly the problem that is explained in the manual:

This whole affair is quite dangerous, as you may block forever.
That is what has happened to you.

One quick way to fix this: Instead of bash, try bash 2>&1. Then $got will get the error message from bash.

To fix this properly, you would need to use the select function. select will tell you whether Reader has anything to read. Then read from Reader only when there is data available. This is difficult to do right, so I recommend that you try something else first.

Probably the best thing is as repson suggested and forget about IPC::Open2. Use $got = qx{$cmd} instead.

In reply to Re: Usage of IPC::Open2 ... by Dominus
in thread Usage of IPC::Open2 ... by galande

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