path_helper: sometimes Apple does kludgy, stupid things

2007-11-18 15:24:00

I've always been quite happy about most of the stuff Apple does. A lot of their solutions to problems are elegant and pretty. However, there are also some cases in which they do awful stuff under the hood. Stuff that makes me cringe in disgust.

Case in point, the new path_helper command.

I've been an avid user of LaTexIT, a LaTex helper programme, for a few months now. It's great how easy it makes the creation of mathematical equations in LaTex.

Unfortunately LaTexIT doesn't yet work flawlessly on Leopard. One of the things that goes wrong is the fact that it just won't start :D After trying to start the app a few times, I noticed a run-away process called path_helper.

I asked Pierre whether path_helper might be tied to the problems he's having, because we don't often get run-away processes. Pierre confirmed that others have hinted at path_helper as well, but that he isn't quite sure yet. Unfortunately he doesn't have a Leopard license yet, so he can't debug the problems yet (hint: make a donation if you use LaTexIt! Pierre could use a Leopard license!).

To help him out, I dug around a little bit. What follows is what I e-mailed Pierre. If you don't want to read through the whole bit, here's the summary:

Apple wants to make it easy to expand the $PATH variable for every user on the system automatically. Instead of tagging on new PATH= lines onto the end of /etc/profile, they've created the path_helper command that gets called by /etc/profile. Path_helper reads directory paths from the text files in /etc/paths.d and appends these paths to $PATH.

So because the want to make it just a -little- easier to add to $PATH, they've:

* Created a new directory structure under /etc/paths.d

* Allow new apps or environments to add text files to /etc/paths.d

* Created a new command which simply reads text files and barfs out shell commands.

* Thus broken the Unix standard way of globally setting $PATH.

Good going Apple! You bunch of schmucks!


Hmm, this seems to be a weird little, extra tool that Apple has tagged onto the OS. I'm not sure if it's the most elegant solution to the problem. I see what they want to do though: they want to be able to easily make adjustments to the $PATH variable for all users on the system.

Personally I'd just use the global profile in /etc, but apparently Apple have chosen a roundabout way.

Each user's .profile calls that path_helper process. The only thing that path_helper does is generate the requisite sh/csh commands to adjust the $PATH variable.

From the manpage:


ath_helper(8) BSD System Manager's Manual path_helper(8)


path_helper -- helper for constructing PATH environment variable


path_helper [-c | -s]


The path_helper utility reads the contents of the files in the directories

/etc/paths.d and /etc/manpaths.d and appends their contents to the PATH and

MANPATH environment variables respectively.

Files in these directories should contain one path element per line.

Prior to reading these directories, default PATH and MANPATH values are

obtained from the files /etc/paths and /etc/manpaths respectively.


-c Generate C-shell commands on stdout. This is the default if SHELL

ends with "csh".

-s Generate Bourne shell commands on stdout. This is the default if

SHELL does not end with "csh".


The path_helper utility should not be invoked directly. It is intended only

for use by the shell profile.

Mac OS X



So instead of putting PATH=$PATH:/usr/whatever/bin in /etc/profile, Apple have decided to make a new config file: /etc/paths.d. This config file will list all directories that need to be appended to the default $PATH.

/me looks at /etc/paths.d

Actually... It's a directory, containing text files with directory paths. For example:


Kilala:~ thomas$ cd /etc

Kilala:etc thomas$ cd paths.d

Kilala:paths.d thomas$ ls


Kilala:paths.d thomas$ ls -al

total 8

drwxr-xr-x 3 root wheel 102 24 sep 05:53 .

drwxr-xr-x 91 root wheel 3094 13 nov 21:11 ..

-rw-r--r-- 1 root wheel 13 24 sep 05:53 X11

Kilala:paths.d thomas$ file X11

X11: ASCII text

Kilala:paths.d thomas$ cat X11



I guess Apple's reasoning is that it's easier to add extra text files to /etc/paths.d, than it is to add a new PATH= line to /etc/profile. Personally, I think it an in-elegant (and rather wasteful) way of doing things :/

Wait, it's even worse! The path_helper gets called from /etc/profile! Ugh! :(


Kilala:~ thomas$ cd /etc

Kilala:etc thomas$ cat profile

# System-wide .profile for sh(1)

if [ -x /usr/libexec/path_helper ]; then

eval `/usr/libexec/path_helper -s`


if [ "${BASH-no}" != "no" ]; then

[ -r /etc/bashrc ] && . /etc/bashrc



Let's see what happens when I run the command...


Kilala:etc thomas$ /usr/libexec/path_helper -s

PATH="/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin"; export PATH

MANPATH="/usr/share/man:/usr/local/share/man:/usr/X11/man"; export MANPATH


What a totally stupid and annoying way of doing this. What's worse, I'm quite sure it also breaks the Unix-compliancy of Leopard when it comes to standards for setting $PATH.

Hmm :/ tags: , , ,

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