exec() replaces the current process with a new one. When you call exec from the perl process that's running your Tk program you replace it with the exec'd process. The solution is to fork() and run exec() from the child process.

The only issue I'm not 100% certain about is the handling of the CHLD signal and child exit status, particularly when exec() fails. Hopefully someone with a better grasp of the issues can help clear that up.

Here's a short example:

#!/usr/bin/perl
use Tk;

sub go {
    local $SIG{CHLD} = 'IGNORE';   # don't wait for child
                                   # exit status. avoids
                                   # zombies.
    die "fork failed: $!" unless defined($pid = fork);
    return if $pid;
    exec("xterm");
    warn "exec failed: $!";
    CORE::exit(1);
}

$m = tkinit; 

$m->Button(-text=>"Foo",-command=>sub{print"Foo\n"})->pack;
$m->Button(-text=>"Go",-command=>\&go)->pack;

MainLoop;
[download]

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.