#!/usr/bin/perl
#!C:/Perl/bin/perl
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The Cygwin shell will look at the 'shebang' line to determine what interpreter to use to run your script. So it will either run the cygwin perl (/usr/bin/perl) or the Activestate one (C:/perl/bin/perl) depending on which you put first. However, if you run it from an XP CMD window, I don't think it pays any attention to the shebang line. It'll be run with whatever perl you use from the command line or whatever perl is associated with it in the registry.

Put differently -- $^O tells you what the executing perl was compiled for, not where it was launched from.

So, I guess you're saying that there is no way to determine "where it was launched from", correct?

See the discussion under $^X in perlvar for ways of discovering the path of the executable being run. That should allow you to determine whether the currently running version of perl is a native or cygwin variant in all but the most extreme cases of deliberate desception.

---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

So, I guess you're saying that there is no way to determine "where it was launched from", correct?

I suspect that other than trying to do some inspection of the process tree, the answer is no.

However, this is sounding like an XY Problem. What are you actually trying to do such that it matters where a Perl binary was launched from?

It seems to me that once a binary is launched, it will behave according to how it was compiled, not how it was launched. The only difference I could imagine would be what the command line argument array looks like and what the inherited environment is.

That might be something to try. E.g. print_env.pl:

#!C:/perl/bin/perl
#!/usr/bin/perl

use strict;
use warnings;

print "\$0: $0\n";
print "ARGV: ", join( q{,}, map { qq('$_') } @ARGV ), "\n";
print "\nEnvironment:\n";
print "$_: $ENV{$_}\n" for sort keys %ENV;
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Run that from cygwin's shell and cmd.exe, try swapping around the shebang lines, etc. From cygwin's shell, try invoking it directly versus calling it as an argument to perl:

$ chmod +x print_env.pl
$ ./print_env.pl one two three
$ perl print_env.pl one two three
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I think if you call it directly, you'll see something different in $0 than if you call it as the argument to perl. And you might see differences in %ENV. You might even set an environment variable in your cygwin .bashrc that you could use as a flag.

-xdg

Code written by xdg and posted on PerlMonks is public domain. It is provided as is with no warranties, express or implied, of any kind. Posted code may not have been tested. Use of posted code is at your own risk.

If you run your script as perl script.pl instead of script.pl or ./script.pl (as the case may be) then I think you'll always get what you want. For me on Cygwin:

Rob@desktop2 ~/pscrpt
$ cat try.pl
#!C:/perl58_M/bin/perl
print $^X, "\n";
print $^O;
Rob@desktop2 ~/pscrpt
$ perl try.pl
/usr/bin/perl.exe
cygwin
Rob@desktop2 ~/pscrpt
$ ./try.pl
C:\perl58_M\bin\perl.exe
MSWin32
Rob@desktop2 ~/pscrpt
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If you want to take advantage of crappy shortcuts, then be prepared to face the associated inconvenience :-)

Cheers,
Rob
Update: Hmmmm ... after about one minute's reflection, it has oocurred to me that I might have missed the point .... (apologies if that's the case).