Re: Success, to some extent

[Roland McGrath <roland@frob.com>]

> nisse@lysator.liu.se (Niels Mvller) writes:
> 
> > A stupid question: Is there any particular reason for not using the
> > /dev/fd/NNN method by default? To me, it sounds more reliable than
> > searching for the file in $PATH.
> 
> Searching in $PATH is entirely reliable because "found it" is measured
> entirely by whether the file's identity is the same, and we have a
> secure way to match file identities, through the io_identity RPC.
> 
> There are reasons why the /dev/fd/NNN version is suboptimal; first,
> the file shows up on a file descriptor that gets inherited by all
> children.  This has security implications that we haven't really
> thought through at all.  Some scripts also might want to look at the
> file name and key off that (a gross programming technique, I agree),
> and they would lose if the file name were always /dev/fd/NNN.

The short version is:

bash$ foo-script
awk: /dev/fd/4:12: syntax error

[auguugh!]  Now imagine it's not you at the bash command line, but
someplace deep in some other shell script run by some huge makefile so you
have to read lots of source to figure out what file /dev/fd/4 really is!
This is not conducive to the use of sanity-preserving tools like M-x
compile mode.