Re: #! syntax

[D-Man <dsh8290@rit.edu>]

On Wed, Feb 28, 2001 at 06:17:35PM +0000, David Wright wrote:
| Quoting D-Man (dsh8290@rit.edu):
| > On Mon, Feb 26, 2001 at 05:50:54PM +0100, Carel Fellinger wrote:
| 
| > | You could consider:
| > | 
| > |    #!/usr/bin/env perl
| > | 
| > | as more installs will have env in the same place.
| > | 
| > 
| > This is the correct way to begin python scripts (I can't say how the
| > perl community feels) :
| > 
| > 
| > #!/usr/bin/env python
| > 
| > # python code here
| 
| Well it's difficult to see much difference between these two
| suggestions.

It's the same, except that I don't know if the perl community takes an
opinion regarding the "correctness" of 

#!/usr/bin/perl 
vs.
#!/usr/bin/env perl


The python community prefers the latter version (s/perl/python of
course).

| 
| > The idea is that env knows where stuff on the current machine is, so
| > simply ask it for the interperter you want (python, perl, bash, etc).
| 
| AFAIK env knows nothing about "where stuff is". It just modifies
| the environment (nothing to do here as it happens) and runs perl
| or python (which are found through $PATH).
| 
| > On a tangent, is there a way to manually configure env as to program
| > locations?  In particular, how can I have env on my cygwin
| > installation know where python is (Win32 python build)?  For now I
| > have my python script in foo.py with a wrapper foo that does :
| > 
| > #!/bin/bash
| > 
| > python foo.py $*
| 
| I'm not sure what your difficulty is. Your $PATH presumably contains
| python so the env trick should work. The env trick is only necessary
| because #! requires the full path: although the path to perl may vary
| on different systems, the path to env is usually the same, /usr/bin/env.
| So you can use one script on the different systems and $PATH (different
| on different systems) will actually find perl, python or whatever.
| 

Hmm, it's working now.  I must not have had python in the path before.
I have a shell script in the path under my home directory that points
to the full path of the python executable.

| If you want to run a specific version of python, then just write its
| path in your script:
| 
| #!/usr/bin/env /weird/path/python32

That defeats the purpose of using env as the first command ;-)


Thanks,
-D