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Re: 20010402: ldm-5.1.3 on linux potato OS

Celia Chen wrote:
> 
> Anne,
> 
> I reloaded ldm-5.1.3 and recompiled it with the change in
> "configure" (line #545: ccs=`gcc`). CC was set to gcc correctly
> for the makefiles by configure with a clean reinstallation. It
> finally compiled and is running now.
> 
> What I don't understand is that it looks like config.cache is
> fixed after the first run of "configure". Reruning "configure"
> after the first run can't change the setup in config.cache. Is
> it safe to remove config.cache before reruning configure?
> (Somthing I didn't try.)
> 
> Thanks for your help.
> 
> Celia

Hi Celia,

Let me make this response a little more complete for the purpose of
making a useful message for our support archives.

From the 'configure' documentation:

"To avoid checking for the same features repeatedly in various configure
scripts (or repeated runs of one script), configure saves the results of
many of its checks in a cache file. If, when a configure script runs, it
finds a cache file, it reads from it the results from previous runs and
avoids rerunning those checks. As a result, configure can run much
faster than if it had to perform all of the checks every time."

So, config.cache serves as input to configure.  configure will generate
config.cache if it doesn't exist.  If it does exist, configure will go
with those contents.   Thus, I would advise editing config.cache, and
not configure.  (Or, you can say './configure --cache-file=<fileName>'
if you want to try a different cache file.) 

Now, when configure tries to determine which C compiler to use, it will
first look to see if CC is set in the environment before checking in
config.cache.  This is why I advised you to 'setenv CC gcc' before
calling configure.

From a support perspective, I want users to be able to upgrade their
LDMs without having to remember to do lots of extra stuff that is unique
to their site.   In your case you'll need to remember to take one extra
step.   When you get a distribution from us, it will provide a new
configure.  At that point you must remember to either copy over the
config.cache file from the previous installation, or set the CC
environment variable again before actually doing the configuration.

Anne
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Anne Wilson                     UCAR Unidata Program            
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                                  Boulder, CO  80307
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