reseting PATH

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I have a problem in pre-pending to PATH for a captive script. I'm trying to append the location of the perl executable I wish to use to the beginning of the PATH and then exec it to pick up the change. Since this perl script is called directly in a captive environment I am unable to set these environment variables in calling script first. This method works fine for other environment variables (I picked this code up from a response to another question by Tye) but not for the PATH.

# Set up the perl executable and library path
BEGIN {
        $ENV{PATH} = "/mypath/perl/bin:$ENV{PATH}";
        $ENV{PERL5LIB} = '/mypath/perl/lib/site_perl/5.8.8/sun4-solari
+s:/mypath/perl/lib/site_perl/5.8.8:/mypath/perl/lib/site_perl:/mypath
+/perl/lib/5.8.8:/mypath/perl/lib/site_perl';
        exec 'env', $^X, $0, @ARGV;
}
[download]

The problem is that when I do the above the executable never returns and I cannot figure out what it is doing. I suspect it is constantly re executing itself in an infinite loop
Any help appreciated

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Re: reseting PATH by Corion (Patriarch) on Apr 11, 2011 at 13:20 UTC
How will your Perl program know that it has already re-executed itself? My approach would be to set a second environment variable to tell your program that it is already re-executing: `warn "$0 launched"; if (! $ENV{RE_EXECUTING}) { $ENV{RE_EXECUTING} = 1; warn "Set up environment. Re-executing now."; exec ... };` [download] But maybe you want to just check whether the environment needs changing at all, and only if you need changes re-execute?	[reply] [d/l]
Re^2: reseting PATH by Anonymous Monk on Apr 11, 2011 at 13:52 UTC
Thanks. I knew the answer was staring me in the face.	[reply]
Re: reseting PATH by ikegami (Patriarch) on Apr 11, 2011 at 16:22 UTC
I think it's safer to pass an argument. Secondly, `env $^X` makes no sense. You want one of `exec $^X, ...` `exec 'env', 'perl', ...` `exec '/mypath/perl/bin/perl', ...` Your other changes would indicate you want the last. Thirdly, the changes to PERL5LIB look redundant with the paths built into the Perl you want to be running. `BEGIN { if (@ARGV && $ARGV[0] eq '--fixed') { shift(@ARGV); } else { $ENV{PATH} = join ':', '/mypath/perl/bin', $ENV{PATH}; delete $ENV{PERL5LIB}; exec '/mypath/perl/bin/perl', $0, '--fixed', @ARGV; die ...; } }` [download]	[reply] [d/l] [select]