topic Which perl question in Operating System - Linux

Which perl question

4ldo — Wed, 24 Jan 2007 17:50:36 GMT

Hi all,

In hp-ux if i start a perl program like "#!/usr/local/bin/perl" and there is no /usr/local/bin/perl binary (or a link to binary), it will go on search my $PATH for perl and execute the program. If I try the same on my laptop (Linux) then it will inform me that there is no interpreter (no /usr/local/bin/perl- even though perl is in my path in /usr/bin) and halt ( which makes sense to me). Do you know why this is happening?

Thanks in advance : )

BR-s,
Alex

Re: Which perl question

A. Clay Stephenson — Wed, 24 Jan 2007 18:05:44 GMT

If there is no /usr/local/bin/perl the script should fail regardless of the platform. I suspect that what is really happening is that the "shebang" line is not the very first line of your script with no leading whitespace. In that case, the shebang becomes a comment.

In any event, generally the least evil approach that I have found is to shebang all perl scripts as:
#!/usr/bin/perl -w
on all platforms. Then for each platform, I create a symbolic link from the actual location to /usr/bin/perl, e.g.
ln -s /usr/local/bin/perl /usr/bin/perl

Once that link is created on each target platform, /usr/bin/perl works every time. This convention even works on Windowes because Windows doesn't observe the shebang convention and treats the line as a comment.

Re: Which perl question

James R. Ferguson — Wed, 24 Jan 2007 19:24:20 GMT

Hi Alex:

To aid in locating your perl binary, you could do:

# whereis perl

Then, as Clay suggests, create any necessary symbolic link from '/usr/bin/perl' to the installed binary and use the standard link as your standard interpreter line.

Regards!

...JRF...

Re: Which perl question

Dennis Handly — Thu, 25 Jan 2007 03:23:40 GMT

One clever trick that I've seen to execute an "interpreter" anywhere in your path is:
#!/usr/bin/env perl

Unfortunately it doesn't appear to let you put any arguments on that line.

Re: Which perl question

dirk dierickx — Mon, 29 Jan 2007 03:46:22 GMT

indeed, 'env; used to be a good solution for these kind of problems, but then again, 'env' is not installed on all systems either...

so in the end i just made sure all systems had a link at the same place to the real location.

Re: Which perl question

4ldo — Mon, 29 Jan 2007 13:01:04 GMT

Thanks a lot for your comments guys.. No have it all clear : )

Cheers Alex

Re: Which perl question

James R. Ferguson — Mon, 29 Jan 2007 13:10:14 GMT

Hi Alex:

We're glad you have found help here. Please read:

http://forums1.itrc.hp.com/service/forums/helptips.do?#28

Regards!

...JRF...