Subject: Re: bug#42704: Documentation of call-process

From: Gregory Heytings <[email-masked]>
Date: Tue, 4 Aug 2020 19:47:55 +0200 (CEST)

>
>> The documentation of 'call-process' doe not make reference to the 
>> variable 'exec-path'.  It should.
>
> The ELisp manual says that, see the node "Subprocess Creation".  This 
> isn't specific to call-process, that variable is used by all the 
> functions that create subprocesses.
>

Indeed.  I still believe that adding the sentence "If PROGRAM is not an 
absolute file name, the variable exec-path contains a list of directories 
to search." in the docstring of call-process (and a similar sentence in 
the docstrings of make-process and call-process-region) would be useful.

>
>> Using '(setenv "PATH" "...")' does not have the expected effect for 
>> 'call-process'.  The environment variable "PATH" is correctly updated, 
>> the variable 'process-environment' is also updated, but what 
>> 'call-process' actually uses to locate the executable is the variable 
>> 'exec-path'.
>
> The changes to the environment variables only affect the environment 
> passed to subprocesses, they don't affect the environment of the Emacs 
> process itself.
>

Indeed.  Creating a subprocess is in between the two (Emacs and the 
subprocess), and I at least would have expected that setting "PATH" would 
have changed the path in which the program executable is searched.

Gregory