PostgreSQL - pg_config -bash: pg_config: command not found

you can install postgresql-devel to get that. in rpm based distro

yum install postgresql-devel

will work

or use

yum provides "*/pg_config"

to get the exact package

In addition to installing postgresql-devel I had to modify the PATH environment variable. E.g. add this to your .bashrc:

export PATH="$PATH:/usr/pgsql-9.4/bin"