Re: env: add -S option (split string for shebang lines in scripts)

[Eric Blake]

On 04/26/2018 02:17 AM, Assaf Gordon wrote:
> Hello,
> 
> Attached an updated patch, hopefully addressing all the issues below.
> Initial documentation also included (seperated into several commits to ease 
> review).
> 
> A renderd html page is available here:
>   http://housegordon.org/files//tmp/env-invocation.html

This is missing support for -P, which is one of the essential features
of FreeBSD env, per their man page:
https://www.freebsd.org/cgi/man.cgi?query=env


     Probably the most common use of env is to find the correct interpreter
     for a script, when the interpreter may be in different directories on
     different systems.  The following example will find the `perl' inter-
     preter by searching through the directories specified by PATH.

           #!/usr/bin/env perl

     One limitation of that example is that it assumes the user's value for
     PATH is set to a value which will find the interpreter you want to exe-
     cute.  The -P option can be used to make sure a specific list of
directo-
     ries is used in the search for utility.  Note that the -S option is
also
     required for this example to work correctly.

           #!/usr/bin/env -S -P/usr/local/bin:/usr/bin perl

     The above finds `perl' only if it is in /usr/local/bin or /usr/bin.
 That
     could be combined with the present value of PATH, to provide more
flexi-
     bility.  Note that spaces are not required between the -S and -P
options:

           #!/usr/bin/env -S-P/usr/local/bin:/usr/bin:${PATH} perl


-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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