ubuntu 18.04 - make install - miss ldconfig?

[boaks]

if libcoap is build on a new system, "make install" installs the libraries at "/usr/local/lib".
But if the coap-client is started, it reports, that the libcoap is missing.
AFAIK, a call of ldconfig is required, but missing. After that, the coap-client executes without that failure.

[obgm]

True, but calling ldconfig on the install directory (or adding it to /etc/ld.so.conf is system configuration. IMO this should not belong into the Makefile's responsibility. @tijuca ?

[tijuca]

I guess then is something miss configured an the system.

I'm not working with Ubuntu but on the following parts Ubuntu and Debian is behaving the same.
O.k. looking at /etc/ld.so.conf we will see that content:

include /etc/ld.so.conf.d/*.conf

And in /etc/ld.so.conf.d/ you will find a file called libc.conf with that content:

# libc default configuration
/usr/local/lib

Which package belongs to /etc/ld.so.conf.d/libc.conf?

$ dpkg -S /etc/ld.so.conf.d/libc.conf
libc-bin: /etc/ld.so.conf.d/libc.conf

But the package libc-bin is an essential package, means this is always installed as it is really essential. 😃

$ apt show libc-bin | grep Essential

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

Essential: yes

In the end ldconfig is configured as default to also respect the folder /usr/local/lib, there aren't normally any further steps needed if you install libcoap into /usr/local and did not configured any specific target folder.
This is also the first complain that using the default installation folder isn't working so far I remember.

OTOH I agree with obgm that ldconfig calls are not part of any installation step.

[obgm]

The question if /usr/local/lib is included somewhere in /etc/ld.so.conf put aside—if changing --prefix during configure, you would have the same issue as described by @boaks. IIRC, the linker outputs a note explicitly stating the steps you might want to make ld find the shared libraries.

[boaks]

My understanding was, that ldconfig updates the "library index/cache".
If you alter something with that libraries, either a "restart" or a explicit call to ldconfig is required.
I called ldconfig in my home directory. After I executed it, the example execs have worked.

[boaks]

The question if /usr/local/lib is included somewhere in /etc/ld.so.conf

Yes, it was, but without refresh the libs-cache with ldconfig, it seems not to work.
If wanted, I may test this with a new ubuntu 18.04 installation.