Problem with 'ldconfig'

[am579]

I am a programmer, and create some libraries which I place in '/usr/local/lib', and some apps in '/usr/local/bin'.
Before running the apps for the first time, I must do 'sudo ldconfig /usr/local/lib'; otherwise, the app won't run 'cos the loader can't link to the libs.
The problem I'm having is that sometimes the problem comes back later (after a restart) and I have to run ldconfig again. Surely it should store the result in a config file and it should be permanent ?
I was having this problem in F16 and now again in F17. I have been working this way for years on Ubuntu and OpenSuse, and not seen this problem. Once I ran ldconfig the apps worked and stayed working.

Or is there a preferred way of doing this ? I.e. is there a recommended alternative to placing my libs and apps in these locations ? Should I use a ENV setting ?

AM

[jpollard]

You need to put a file in /etc/ld.so.conf.d that contains the path to the library.

Then, on each boot it will be used in the ldconfig, and anytime the ld.so.cache file gets rebuilt it will include the path.

forgot - the file should be named <library-name>.conf. the ".conf" is required.

[PabloTwo]

When placing your shared object files in non-standard locations, you should create a file /etc/ld.so.conf.d/ and name it something.conf, (i.e. my-apps.conf). In that file, just put the full path to the directory where those reside (i.e. /usr/local/lib).

Then you won't need to specify that path when running the ldconfig command, as ldconfig should use all the paths specified in the *.conf files in the /etc/ld.so.conf.d/ directory.

ldconfig stores it's data in /etc/ld.so.cache. I don't know/understand why ldconfig is losing your links from previous runs of ldconfig.

[am579]

Thanks, I've done that and it works so far ! PabloTwo's comment is valid, though, I reckon...once I had used the proper ldconfig command it should remember the result indefinitely, shouldn't it ?

[PabloTwo]

The /sbin/ldconfig command is executable by everyone:

-rwxr-xr-x. 1 root root 960088 May 14 15:39 /sbin/ldconfig

The /etc/ld.so.cache file is writable only by root:

-rw-r--r--. 1 root root 143422 May 29 14:13 /etc/ld.so.cache

So, if you were not issuing the ldconfig command as root, it would not have saved anything to the cache file. You should always run ldconfig as root if you want the results to persist between boots. Maybe this was the problem?

[mschwendt]

The answer is hidden in the earlier replies. /usr/local/lib is not in the list of library search paths. Running "sudo ldconfig /usr/local/lib" adds the path for only that single run of ldconfig. That updates the ld.so.cache file correctly, but subsequent runs of ldconfig (manually or as part of RPM scriptlets) overwrite the cache and don't look in /usr/local/lib by default. Hence you've had to add the path permanently via a file in /etc/ld.so.conf.d/

[goodfella]

What does "echo $LD_LIBRARY_PATH" say?
Should be: /usr/local/lib:/usr/lib:/lib

Just checking that you did this first.

What about:
echo $PKG_CONFIG_PATH
/usr/local/lib/pkgconfig:/usr/lib/pkgconfig: