./configure generates the error "ptlib-config" missing

[KG7QIN]

Running ./configure generates the error:

....
checking openr2.h usability... yes
checking openr2.h presence... yes
checking for openr2.h... yes
checking /home/olivas/pwlib/include/ptlib.h usability... no
checking /home/olivas/pwlib/include/ptlib.h presence... no
checking for /home/olivas/pwlib/include/ptlib.h... no
checking /usr/local/include/ptlib.h usability... no
checking /usr/local/include/ptlib.h presence... no
checking for /usr/local/include/ptlib.h... no
checking /usr/include/ptlib.h usability... yes
checking /usr/include/ptlib.h presence... yes
checking for /usr/include/ptlib.h... yes
checking for ptlib-config... no
./configure: line 25817: --ldflags: command not found
Cannot find ptlib-config - please install and try again

[KG7QIN]

To fix, use this:

export PTLIB_CONFIG=/usr/share/ptlib/make/ptlib-config

(or the equivalent)

./configure will work just fine.