for the error, try to cd into directory before runing command, inside script.
For db2 backup, to have this script work, you need to put your databases in archive logging mode, or you need to quiesce database before backup, and do "offline" backup.
I am not very sure what is the point of backing up open transaction log files, but maybe this is ok, I do not know.
What else you can do, if your database is in archive log mode, you can point your archive logs to have primary location going directly to TSM.