Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Fri, 18 Jan 2013 17:19:18 -0600

Hi,

On 2013-01-18 Ralph Lange wrote:
> A more elegant portable solution is replacing the hashbang with
> 
>     eval 'exec perl -S $0 ${1+"$@"}' # -*- Mode: perl -*-
>         if 0;
> 
> That will find perl in the PATH.

It seems the recommended way to handle this has changed a bit over the years. 
The current trend for both Perl and Python seems to be to use /usr/bin/env, 
which finds perl in the path without being quite so verbose:

#!/usr/bin/env perl

All modern Unix-type systems understand the #! line and have the env program 
in /usr/bin — even Solaris and Cygwin.  The magical parts in the above eval 
were needed to get around various specific shells that might be executing the 
script, but I don't believe anyone will be trying to run EPICS on the exotic 
ones nowadays (and they're not needed if the script has a #! line).

Windows does not understand either the #! line or any of the above magic, so 
the EPICS build system always explicitly includes $(PERL) in the command line 
and I think manually running perl scripts will always require that too.

I propose to change the preamble of all the Perl scripts in base-3.14 to the 
above; any objections?  There's a patch file of the necessary changes at
  http://www.aps.anl.gov/epics/base/R3-14/12-docs/envPerl.patch

- Andrew
-- 
There is no such thing as a free lunch.  When invited for lunch,
it is best to check if you are there to eat, or to be eaten.
-- Clive Robinson

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System