I have a script that I need to relocate to a new path. The script's guts (C libs that shouldn't be changed) use some code that basically requires the original path name to be there in the C argv[0] (Perl's $0). Let's say /desired/path is the path that the code expects, and /my/newpath is the place I'm trying to run it from.

First I tried:

$0 = "/desired/path";

That worked! But only on some flavors of Linux and not others. The camel book says this isn't portable so that's not too surprising. Then I tried many incarnations of getting execvp to fool the script. My first attempt:

#!/usr/bin/perl                                                                 
                                                                                
use strict;                                                                     
use warnings;                                                                   
                                                                                
my $desired_path = "/desired/path";                                  
if ($0 ne $desired_path) {                                                      
    warn($0);                                                                   
    exec { $0 } $desired_path, @ARGV;                                           
    exit;                                                                       
}                                                                               
                                                                                
warn("Success!");

That infinitely recurses since $0 always appears to be /my/newpath. This behavior as all other behavior that follows seems to be independent of Linux flavor unlike the direct setting of $0.

Suspecting the multiple levels of exec indirection between the shell and Perl I tried;

exec { $^X } $desired_path, $0, @ARGV;

No dice. Same recursion. I tried it right in the shell also:

> exec -a /desired/path /my/newpath

Also no dice. Any advice on how to get this problem solved on most flavors of Linux?

In reply to Faking Script Names by 3John

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