Re: Modifying %ENV From The Shebang Line

I tried the first shebang line on my FreeBSD system, and it also failed. From looking at the truss output, it seems that the system uses execve(2) to call the shebang interpreter. So I looked at the execve manpage and found this paragraph:

     An interpreter file begins with a line of the form:

           #! interpreter arg

     When an interpreter file is execve'd, the system actually execve's the
     specified interpreter.  If the optional arg is specified, it becomes the
     first argument to the interpreter, and the name of the originally
     execve'd file becomes the second argument; otherwise, the name of the
     originally execve'd file becomes the first argument.  The original argu-
     ments are shifted over to become the subsequent arguments.  The zeroth
     argument is set to the specified interpreter.

Note: it's arg (singular). The manpage claims that this is POSIX standard, so it might apply to Linux, too.

Comment on Re: Modifying %ENV From The Shebang Line

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Re^2: Modifying %ENV From The Shebang Line by williams (Beadle) on Dec 17, 2007 at 23:28 UTC
Maybe that explains some of the results I've seen, where it appears everything after `interpreter` is glommed into a single argument. I'm now left with attempts like the following, which just churn the CPU and never start Perl. `#!/bin/bash eval 'LD_LIBRARY_PATH=/my/lib /usr/bin/perl /the/script' if $runningUnderSomeShell; warn "$ENV{LD_LIBRARY_PATH}\n";` [download] Again, this is based on `perlrun`, though I'm obviously doing something wrong. Thanks, Jim	[reply] [d/l] [select]

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Re^2: Modifying %ENV From The Shebang Line
by williams (Beadle) on Dec 17, 2007 at 23:28 UTC

interpreter

   #!/bin/bash
   eval 'LD_LIBRARY_PATH=/my/lib /usr/bin/perl /the/script'
      if $runningUnderSomeShell;

   warn "$ENV{LD_LIBRARY_PATH}\n";
[download]

perlrun

Thanks,

Jim

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