[OS X TeX] Leopard MacTeX PATH problems, still
amorton at fastmail.fm
Sun Mar 23 00:31:16 EDT 2008
> The /usr/libexec/path_helper utility is itself a shell script that
> takes care of parsing /etc/paths.d/; one interesting thing to note
> is that any paths in the text file /etc/paths will get processed
> ahead of the remaining paths.
> So if there is anything in that file that might cause trouble by
> coming first, then you must either chance editing (and remembering) /
> etc/paths, or else you must shortcut the default behavior by having
> your system-wide shell file NOT call path_helper, and then call it
> manually AFTER you have set the other paths first.
It's more subtle even than that. Anything that's in the shell's
initial PATH before path_helper is called (eg. from /etc/profile) will
always appear first, regardless of the order in /etc/paths.
In practice this means that /usr/bin, /bin, /usr/sbin and /sbin will
always come first in a Leopard PATH, unless a script alters PATH
This means that if you install your own version of an Apple-supplied
utility, for example a custom 'tar' in /usr/local/bin, then the shell
will continue to prefer the Apple-supplied version unless you invoke
it expicitly as /usr/local/bin/tar.
People have complained that this is the opposite of the 'conventional'
Unix approach, where locally-managed hierarchies like /usr/local/bin
come first in PATH. This way, a local user runs 'tar' and gets
whatever version of tar is deemed locally appropriate, while those
wanting 'factory default' behaviour invoke /usr/bin/tar explicitly.
The path_helper way of doing it means that 'tar' is guaranteed to give
you the vendor's supplied tar no matter what, so is helpful from this
perspective; but of course this guarantee breaks as soon as you go to
a non-Leopard system, or as soon as a user hacks their own PATH. '/
usr/bin/tar' is still the only way to access the default tar that's
always guaranteed to work. Meanwhile, anyone wanting a local
alternative tar must run /usr/local/bin/tar: so arguably you're
requiring more work from some users while not reducing the work
required by others.
The distinction of course only matters where someone is installing
their own version of a supplied utility - it doesn't matter for TeX or
anything else that doesn't arrive out of the box.
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