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copied!<p>Your current script doesn't even change an environment variable in the Perl script itself. Rather, it invokes a shell as a subprocess; that shell process executes <code>. /root/.profile</code>, which updates <code>$LD_LIBRARY_PATH</code> only in that shell process.</p> <p>You can change an environment variable in a Perl script (more precisely, in the process running the Perl script) by updating <code>%ENV</code>:</p> <pre><code>$ENV{LD_LIBRARY_PATH} = '/'; # or some more reasonable value </code></pre> <p>As <code>perldoc -v %ENV</code> says:</p> <blockquote> <p><code>%ENV</code> The hash <code>%ENV</code> contains your current environment. Setting a value in "ENV" changes the environment for any child processes you subsequently "<code>fork()</code>" off.</p> </blockquote> <p>But that probably still won't do what you want; it won't (and can't) affect the environment of the process that invokes the Perl script (your interactive shell), only the Perl process itself and anything it invokes.</p> <p>I'll assume you want to update <code>$LD_LIBRARY_PATH</code> in your current interactive shell process. To do that, you can have you Perl script <em>print a shell command</em> that will update <code>$LD_LIBRARY_PATH</code>. Then, rather than simply running your Perl script, you can execute it and then evaluate its output. For example:</p> <pre><code>$ cat env.pl #!/usr/bin/perl use strict; use warnings; print "export LD_LIBRARY_PATH=/\n"; $ ./env.pl # just prints the command without executing it export LD_LIBRARY_PATH=/ $ eval $(./env.pl) # executes the command in the current shell $ echo $LD_LIBRARY_PATH / $ </code></pre> <p>This assumes that your current shell is bash or something similar.</p> <p>Another option: After modifying <code>%ENV</code>, your Perl script can invoke another command, even a new interactive shell. The new process will inherit its environment from the Perl script. This can be a bit cumbersome, though; for example, if the new process is an interactive shell, it won't inherit <em>unexported</em> variables or history from the parent shell.</p> <p>(One note, not directly related to your question: The fact that you're messing with <code>/root/.profile</code> implies that you're doing things as <code>root</code> (superuser). This can be dangerous. Use the <code>root</code> account (either by logging into it or via <code>sudo</code> only for things that actually need root privileges. For anything else, use a personal user account.</p>

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