Please also check that PKG_CONFIG_PATH contains ${libdir}/pkgconfig
 

I'm installing libgphoto and the configure script tells me to:

"Please also check that PKG_CONFIG_PATH contains ${libdir}/pkgconfig"

How do I do this? I've typed echo $PATH and it doesn't mention anything like this, so what do I do?

Maybe....
 

That may be something in your /etc/profile.
or perhaps /.bash_profile?
??

Or maybe something in the configure script of the package you're installing?

I don't think so. I can't find a /.bash_profile and /etc/profile doesn't look helpful.

Is it something to do with typing ln -s ?
I think I'm trying to add a directory to my $PATH, or is it to a $PKG_CONFIG_PATH?

Yeah it says this in the readme:

"Please check the output of the configure script for whether all
desired libraries have been detected correctly. E.g., you might
have to add the path where libusb-config resides to your PATH
before running configure."

I know the directory, but how do I add it to my PATH?

EXPORT
 

export PATH=$PATH:/dir/you/want/to/add (that's a colon between $PATH and /dir)

or you could add it to
/home/yourname/bash_profile

Sorry, that was just me being lazy and not working it out by myself.
One last thing: I've got "PATH=$PATH:$HOME/bin"
in .bash_profile, is it OK to just add the new directory on the end of this statement, seperated by a colon, or do I add it on the next line?

Sure!
 

You can add it. (colon separated)
Note that the order listed is the order in which your computer looks for stuff.