[syslinux] PATH directive rules

[Ady]

> On Tue, 2013-01-29 at 10:48 +0200, Ady wrote:
> > > But for all variants, wherever we find ldlinux.c32, that's used as the
> > > initial PATH string.
> > > 
> >  
> > Thank you for your answers.
> > 
> > I want to understand what exactly the word "initial" means here. 
> 
> It's used as the PATH string before any PATH directives are parsed in
> config files,
> ...
 
According to your answer for the example at the end of your previous 
email ("B, C, D, E", posted below too), the location where 
ldlinux.c32 resides indeed is always searched-for before the paths 
stated by the PATH directive,... 

> ...
> config files, meaning that the location of ldlinux.c32 will always be
> the first string in PATH, since PATH directives can only be appended.
 
 ... but it is not the "first" searched-for location. Maybe using 
terms like "first string in PATH" in this case is technically correct 
(or not; I don't know), but I am trying to make it clearer for simple 
common mortal users as myself :).
 
> 
> > What happens with the searched-for paths when using the CONFIG directive 
> > to change the CWD? Is the new CWD added to the searched-for paths? Is 
> > the "old" (previously set as - but no longer is the) CWD still 
> > included in the searched-for paths?
> 
> If the old CWD is the directory in which we found ldlinux.c32, then it
> will be included in PATH.
> 
> But remember that the CWD is *always* searched before the entries in
> PATH.

Yes; according to your answer for the example at the end of your 
previous email ("B, C, D, E", posted below too), the "CWD" is the 
first location to be searched-for, _then_ the location where 
ldlinux.c32 resides and only _then_ the locations according to the 
PATH directive(s).

> 
> > Having now:
> > A_ "old" CWD;
> > B_ "new" CWD;
> > C_ ldlinux.c32 location;
> > D_ PATH directive(s) stated in "old" cfg files;
> > E_ PATH directive(s) stated in "new" cfg files;
> > 
> > in which specific (sort) order are the respective paths searched for 
> > lib*.c32 files?
> 
> B, C, D, E. Note that A is not searched unless it's equal to one of the
> other letters.
> 
> Make sense?
> 
 
It indeed makes sense, at least until (and if) the location where the 
main c32 module that needs the lib*.c32 file(s) is also added to the 
fallback rules for the PATH directive.


So, if I understand correctly...

1_ The CWD is always first; and if the CWD changes (by means of the 
CONFIG directive), then the new CWD will be the new first location to 
be searched-for, and the "old" CWD is not retained.

2_ Then, if the needed lib*.c32 files were not found in the CWD, the 
location of ldlinux.c32 is the second path to be searched-for. Since 
this second path is (still) known (retained?) and available after 
using the CONFIG directive, it can be searched-for, still as _second_ 
possible location, while the new first searched-for path will be the 
new CWD.

3_ The paths in all PATH directive statements are searched-for, in 
the same order they are stated, and are also available after using 
the CONFIG directive, still with lower priority than the new CWD and 
than the location of the ldlinux.c32 file.

5_ Any new PATH statement always appends new locations to the 
previous paths already available, so the presence of a new PATH 
directive does not replace previous PATH statements, even if those 
previous paths are not stated in the current cfg file.

I know that the above seems "too long". Some of us need it; some may 
be bored already.

The above comments ("rules"?) are not including "every possible" 
situation, but I think they probably cover many of them. Hopefully, 
the above comments are accurate enough in this context. If they are 
not, please correct them.

Thank you,
Ady.