What is pkg-config supposed to do?

I'm installing additional software and getting error message that include using pkg-config to find the library or something. I tried using pkg-config in a few different instances and none of them seemed to worked.

I tried
Quote:

bash-4.3# pkg-config --modversion vi Package vi was not found in the pkg-config search path. Perhaps you should add the directory containing `vi.pc' to the PKG_CONFIG_PATH environment variable No package 'vi' found

vi is definitely installed. Am I supposed to do something to get pkg-config to work?

Code:bash-4.3# echo $PKG_CONFIG_PATH
/usr/local/lib64/pkgconfig:/usr/local/share/pkgconfig:/usr/lib64/pkgconfig:/usr/share/pkgconfigI did find this
https://www.linuxquestions.org/quest...ig-4175591082/
but nothing happens:
Quote:

bash-4.3# pkgconfig --modversion grep bash: pkgconfig: command not found