Re: "source" shell commands

[Barry Margolin]

In article <85wt16btg5.fsf@lola.goethe.zz>, David Kastrup <dak@gnu.org> 
wrote:

> Tassilo Horn <tassilo@member.fsf.org> writes:
> 
> > Matthew Flaschen <matthew.flaschen@gatech.edu> writes:
> >
> >> Is there an elisp function to "source" a shell file; i.e. an
> >> alternative to:
> >>
> >> (shell-command (concat "source \"" (expand-file-name "~/.rc") "\""))
> >
> > Sure.
> >
> > --8<---------------cut here---------------start------------->8---
> > (defun mf-source (file)
> >   (interactive "f")
> >   (shell-command (concat "source \"" file "\"")))
> > --8<---------------cut here---------------end--------------->8---
> 
> Quoting is always good for trouble.  I'd rather use
> 
> (defun mf-source (file)
>   (interactive "f")
>   (call-process shell-file-name nil nil nil "source" file))
> 
> assuming that you don't care about the output.

First of all, shells don't take a command line to execute as arguments.  
Take a look at what happens if you try it from the command line:

$ bash source .bashrc
source: source: No such file or directory

You can do it with the -c option, but then they expect the command to be 
in a single argument:

(call-process shell-file-name nil nil nil 
              "-c" (format "source '%s'" file))

Second, the point of "sourcing" is to execute the commands in the 
current process's context.  Since call-process and shell-command both 
execute a child process, nothing that occurs in the sourced script will 
have any effect on the emacs process.  So even if you get the syntax 
right, it won't do anything different from executing the script normally.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
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