There is a laptop on which I have no root privilege.
onto the machine I have a library installed using configure --prefix=$HOME/.usr
.
after that, I got these files in ~/.usr/lib
:
libXX.so.16.0.0
libXX.so.16
libXX.so
libXX.la
libXX.a
when I compile a program that invokes one of function provided by the library with this command :
gcc XXX.c -o xxx.out -L$HOME/.usr/lib -lXX
xxx.out was generated without warning, but when I run it error like this was thrown:
./xxx.out: error while loading shared libraries: libXX.so.16: cannot open shared object file: No such file or directory
, though libXX.so.16
resides there.
my clue-less assumption is that ~/.usr/lib
wasn't searched when xxx.out is invoked.
but what can I do to specify path of .so , in order that xxx.out can look there for .so file?
An addition is when I feed -static
to gcc, another error happens like this:
undefined reference to `function_proviced_by_the_very_librar'
It seems .so
does not matter even though -L
and -l
are given to gcc.
what should I do to build a usable exe with that library?
I found a useful article at tldp about this.
It introduces static/shared/dynamic loaded library, as well as some example code to use them.
The way to change a package library location is to manually set it on a startup file i.e. folder) or project-level (located at the current working directory).
6. Which option of GCC compiler provides the linking with shared libraries? Explanation: None.
There are two ways to achieve that:
-rpath
linker option:gcc XXX.c -o xxx.out -L$HOME/.usr/lib -lXX -Wl,-rpath=/home/user/.usr/lib
Use LD_LIBRARY_PATH
environment variable - put this line in your ~/.bashrc
file:
export LD_LIBRARY_PATH=/home/user/.usr/lib
This will work even for a pre-generated binaries, so you can for example download some packages from the debian.org, unpack the binaries and shared libraries into your home directory, and launch them without recompiling.
For a quick test, you can also do (in bash at least):
LD_LIBRARY_PATH=/home/user/.usr/lib ./xxx.out
which has the advantage of not changing your library path for everything else.
Should it be LIBRARY_PATH
instead of LD_LIBRARY_PATH
.
gcc checks for LIBRARY_PATH
which can be seen with -v
option
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