You did not mention what happened what you tried it from a different computer. If it did not work from the other computer as well then it is a server issue, otherwise it is client issue.
To execute the above commands simply launch adadmin utility.
Login into linux as Oracle.
go into Apps home folder
cd PROD
cd AP*
cd AP*
cd AP*
how source the environment file.
. <The environment file name>.env

To view teh name of the environment file you can do the following:
ls *.env

Once the environment is sourced, simply enter adadmin. This will launch the utility. You will see various options. Select the option as indicated by Oracle.