On a more serious node, the exec() is a safe (Edit: not safe as in safety and security) way to achieve what the question asked as my use-case demonstrated. It is true that unless one executes the "trick" from an interactive shell any command past that exec will not run as KurtZ whines rightly points out. For example as a cron job.

I don't see it as a "trick" because this is what exec() was intended to do in the first place. It is not exploiting any of its features=bugs, it is not using it in a heads-down-feet-up kind of way.

And definetely the result is not an illusion because it's there. You get your environment modified albeit within a brand new shell which inherits from the parent shell. It inherits env variables and even opened file descriptors. For example:

exec 3> /tmp/out
echo 'before exec' >&3
exec env2.pl
echo 'after exec' >&3
exec 3>&-
cat /tmp/out
   before exec
   after exec
[download]

So, not a trick, not an illusion but limited (and what isn't) to interactive shells.

For non-interactive use, e.g. a cron-job one can go with corion's Re: setenv in perl. And if only 1 env-variable needs to be set up, then the eval can be avoided by using:

export test=`perl -e 'print 'TURE'`
[download]

Lastly, if the scenario is to run a shell command which reads data from the environment and having a perl script to calculate this data and export it to the environment then why not let perl calculate AND spawn the command because any system() call inherits perl's environment vars, like so:

#!/usr/bin/env perl

$ENV{test} = 'TURE'; # calculate
my @cmd = ('command-exec', 'args');
system(@cmd); # spawn

# simple demo:
system('echo $test'); # prints what
[download]

bw, bliako

---

---

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.