Hi Hitesh,
This should probably be a new thread as this seems to be a different error.
The error you are mentioning sounds like an O/S error saying there is no executable for isql in the PATH environment variable.
Example type command:
which isql
This should bring back the location of the isql executable.
What installation are you working with?
Do you see the isql executable in:
$SYBASE/$SYBASE_OCS/bin
If so, can you run isql with:
./isql -v
Regards,
Ryan