Subject: Re: Tilde is expanded in $PATH, inconsistent behavior
Date: Mon, 27 Jan 2025 15:21:06 -0500
Keith Thompson <keith.s.thomp...@gmail.com> writes:
> The "Tilde Expansion" section of the bash manual does talk about
> using '~' when setting $PATH, but that applies only when setting
> it, not when using a $PATH containing literal '~' characters.
>
> A user who doesn't realize that, for example, "$HOME/bin" is
> expanded in double quotes but "~/bin" is not might end up with
> a $PATH setting that allows direct execution of some commands
> from the bash prompt, but those same commands can't be found by
> other tools.
The problem is a bit subtle. The core point is a fact which is diffused
through Un*x systems, that "~" works only because the shell deliberately
makes substitutions to make it work. In the simplest case, this command
$ ~/bin/clean
works *only* because the shell translates it to
"/home/worley/bin/clean". The shell then hands that string to the
kernel, the kernel finds the file, and executes it.
On the other hand
$ '~/bin/clean'
bash: ~/bin/clean: No such file or directory
Within that context, if an element of PATH contains a '~' character, you
don't expect that to cause execution requests to look in your home
directory, because '~' isn't the name of your home directory.
For that matter, Bash doesn't search the path for executables; the
kernel uses the PATH of the process to find the file whose execution was
requested.
Dale
