I am having an interesting problem. In my last post, I noted that on some Macs with Leopard installed, deactivating the lines calling /usr/libexec/path_helper in the /etc/profile file fixed LaTeXit hanging at launch. A bit more investigation by Antonio Molins (posted in the comments to that post) revealed it was possible to add an ASCII file in the /etc/paths.d directory. We could create a file called /etc/paths.d/macports containing the only the line 

/opt/local/bin
and it should automatically add everything in macports to most user’s PATH variables. However, when I tried this, all my calls to /usr/libexec/path_helper -s always locked up the command.

Some further investigation revealed new user accounts on my Macs didn’t have this problem. I surmised that since I was setting up the PATH and MANPATH variables in my environment at login, that this could apparently lock up path_helper. Since I use tcsh by default (instead of Apple’s default bash shell), I issued the following two commands from the command line

unsetenv PATH
unsetenv MANPATH

and sure enough path_helper worked without an issue. So something is buggy in path_helper, or at least hypersensitive to pre-existing PATH environmental variables. I’ll have to investigate this more later. One thing I did discover is that

/usr/libexec/path_helper -c

will produce the commands to set up tcsh’s environment.

/usr/libexec/path_helper -s

returns those for the default bash shell.