Re: Why does /QOpenSys link to itself

[Scott Klement <midrange-l@xxxxxxxxxxxxxxxx>]

Hi Simon,

> Does any one know why /QOpenSys contains a symbolic link to itself? / 
> QOpenSys/QOpenSys/QOpenSys ..... ad infinitum.

I used to know the answer to this, and it made a lot of sense to me at 
the time, but now I can't remember what the answer was.

I hesitate to answer, because I might get it wrong.

My understand is that it's due to the fact that most PASE software runs 
in /QOpenSys.  PASE software is compiled for AIX, and in AIX, software 
expects to have certain standard directories like /usr, /usr/local, 
/usr/bin, etc.   However, in PASE instead of (for example) /usr/bin, 
they're actually (for example) /QOpenSys/usr/bin.

So PASE plays a trick on the program where it adds a /QOpenSys to the 
start of the path name.  So the program specifies /usr/bin, and PASE 
actually directs it to /QOpenSys/usr/bin

The problem is, what happens when a program (perhaps from user input) 
actually DOES specify /QOpenSys/usr/bin?   Because PASE adds /QOpenSys 
to the beginning, you'd have /QOpenSys/QOpenSys/usr/bin which would be a 
problem -- and that's where the symlink comes in.  If you specify 
/QOpenSys/QOpenSys/usr/bin it's the same directory as /QOpenSys/usr/bin 
thanks to the symlink.

Hopefully I got that right.