Using library files in Linux

Question

I'm trying to use some of the functions that are in the /lib/libproc-3.2.6.so library in my Ubuntu distribution.

I have downloaded and installed the header files and they are defined in my source files.

Currently, this is all I'm trying to do, just for starters...

proc_t **read_proc = readproctab(0);

But I get the following compiler error:

/tmp/cclqMImG.o: In function `Sysmon::initialise_sysmon()':
sysmon.cpp:(.text+0x494): undefined reference to `readproctab'
collect2: ld returned 1 exit status

I'm aware I'm probably doing some wrong with the command I'm using to compile it, but due to lack of experience I'm not sure what I'm doing wrong. This is the g++ command I'm using to compile my cpp file:

g++ -o sysmon.o sysmon.cpp `pkg-config --libs --cflags gtk+-2.0`

Can someone please give me some pointers as to where I'm going wrong.

Answer 1

You are not linking your executable against libproc (that is a linker error message).

Try adding -lproc to the linker command.

Answer 2

You are not actually linking against the library that you wish to use, you are merely including its header files, therefor, the compiler will complain about undefined references.

You can read up on linking against shared libraries here.

A small suggestion, start using the build tool SCons, it can take care of linking to libraries for you, just add the ones you wish to use in the SConstruct file required by SCons and then you don't have to mess about with compiler specifics. You also gain lots of other good stuff that SCons provide. It's highly recommended.

Answer 3

Ubuntu 17.04

You probably want to use -lprocps instead of -lproc.