Normally, you use the File > Exit command to exit from DBISQL. If in an emergency you need to stop DBISQL from the UNIX command level, make sure you stop the right process. When you start DBISQL, two processes are started: a shell process running the dbisql executable, and the Java executable process that runs from the $SYBASE/ASIQ-12_6/jre/bin/native_threads directory. The Java executable is the process you need to kill.
Use a command like the following to find both processes:
ps -ef | egrep "jre|java|dbisql"
ami 1712 21442 0 12:01:17 pts/11 0:00 /bin/sh /mysystem/ami/ASIQ-12_6/bin/dbisql ami 1748 21894 0 12:10:13 pts/14 0:00 egrep jre|java|dbisql ami 1715 1712 0 12:01:18 pts/11 0:07 /mysystem/ami/ASIQ-12_6/jre/bin/../bin/sparc/native_threa
Then use a command like kill -9 to kill the process id for the Java process, which has jre in the path, for example:
kill -9 1715