a "script-relative" version of env

[E R]

Hi all,

This is not a bash bug, but I am hoping the people on this list would
find the question interesting...

I have found it useful to have a "script-relative" version of
/usr/bin/env. Whereas env determines an interpreter's location based
on PATH, this version would determine the interpreter's location based
on the location of the script.

Example - the shebang line:

#!/usr/bin/relexec ../bin/perl

would execute the interpreter ../bin/perl relative to the location of
the script. The argv array of relexec will be:

argv[0] = "/usr/bin/relexec"
argv[1] = "../bin/perl"
argv[2] = "/some/path/to/script"

In this case relexec would exec /some/path/to/bin/perl with the
arguments in argv starting from argv[2].

If anyone is interested I can explain why/how I use this.

Questions:
 - Does something like this already exist?

 - I've noticed that the argument passed to the she-bang interpreter
always seems to be an absolute path when commands are executed from a
shell. Are there cases where that will not be true?