Re: PSA: Mac OS X El Capitan upgrade might break your $PATH

[Andrew Janke <andrew@apjanke.net>]

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On 7/31/15 6:01 PM, Kurtis Rader wrote:
> On Fri, Jul 31, 2015 at 2:05 PM, Andrew Janke <andrew@apjanke.net 
> <mailto:andrew@apjanke.net>> wrote:
>
>
>     I suspect the order of entries in path_helper is determined by
>     alphabetical ordering of the filenames in /etc/paths.d, where
>     path_helper locates the files that come after the default system
>     paths. That "40-" in XQuartz looks like an rcdir-style technique
>     to enforce ordering, and I think the XQuartz folks know what
>     they're doing with the OS X system stuff. (This is on 10.9.)
>
>
> That would be fine if it simply appended those directories in that 
> order to the existing PATH as the man page claims. But it is clearly 
> using a hash based ordering and ignoring even the apparent ordering 
> implied by the file names in /etc/paths.d. From my system:
>
> 14:45 macbook  coff  ~  ls /etc/paths.d
> 40-XQuartzgo
> 14:50 macbook  coff  ~  cat /etc/paths.d/*
> /opt/X11/bin
> /usr/local/go/bin
> 14:52 macbook  coff  ~  /usr/libexec/path_helper -s
> PATH="/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin:/usr/local/go/bin:/Users/krader/bin:/Users/krader/sbin:/Users/krader/symlinks:/usr/local/sbin"; 
> export PATH;
> 14:52 macbook  coff  ~  echo $PATH
> /Users/krader/bin:/Users/krader/sbin:/Users/krader/symlinks:/usr/local/bin:/usr/local/go/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:/opt/X11/bin
>
That path_helper output doesn't look random or hash based. That looks like:

- the system default paths (from /etc/paths) come first, in the order 
specified in /etc/paths
/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:

- then the stuff from /etc/paths.d, in filename alphabetical order
/opt/X11/bin:/usr/local/go/bin:

- then any other item it found in $PATH at the time of its invocation, 
in the order in which they appeared in $PATH.
/Users/krader/bin:/Users/krader/sbin:/Users/krader/symlinks:/usr/local/sbin

That lastpart isn't documented in `man path_helper`, but it behaved this 
way consistently when I was testing it with various $PATH values. (on 10.9)

The man page could stand tobe more thorough and clear, but I don't think 
it's randomly rearranging your path. And the `man path_helper` page does 
indicate where the default paths come from, though it's buried a few 
paragraphs down.

      Prior to reading these directories, default PATH and MANPATH 
values are
      obtained from the files /etc/paths and /etc/manpaths respectively.

>
>     One other El Capitan change: the system-supplied zsh (5.0.8)
>     appears to be compiled with /usr/local/share/zsh/site-functions in
>     the default $fpath, which was not the case for earlier versions of
>     OS X. This is probably related to the "rootless" stuff that locks
>     down /usr outside /usr/local/.
>
>
> Yes, I noticed that as well and should have mentioned it as it causes 
> zsh running as root to complain about "compinit: insecure files" since 
> those files are managed by HomeBrew and owned by me.
> Computer Security: If it isn't getting in your way you're doing it 
> wrong :-)
> -- 
> Kurtis Rader
> Caretaker of the exceptional canines Junior and Hank