z/VM: CP Commands and Utilities Reference - z/VM - IBM

DEFINE COMMAND / CMD
Responses
9. To remove the command processing code from CP’s system execution space,
use the CPXUNLOAD command (page 107).
10. When specifying a command or subcommand name, you can use special
characters in the name. However, we do not recommend that you use the
pattern matching characters (* and %). You can use these characters to define
commands, but they may seem confusing when you issue the LOCATE
CMDBK command. For example, suppose you define 2 new commands:
CPU% — to calculate recent CPU busy as a percentage, and CPU1 — to
cause some action on real processor number 1. If you issue LOCATE CMDBK
CPU%, CP displays information on both CPU% and CPU1, because CP
interprets the % in your LOCATE command to be a pattern matching character.
CP places no restriction on the use of special characters such as *, %,
comma, (, ), blank, /, ;, $, #, and @ in command names. However, some
External Security Managers (EMSs) restrict their use. Please consult your ESM
documentation for information on restricted characters.
11. If you try to define a minimum abbreviation that matches the abbreviation for
an existing command, subcommand, or alias, CP rejects your DEFINE
command. For example, if you created a “QUEUE” command with a minimum
abbreviation of 2, CP would reject your QUEUE command because “QU” is an
abbreviation for the QUERY command. In this case, you would need to specify
a minimum abbreviation greater than or equal to 4 because the first 3
characters of QUERY and QUEUE are identical.
12. Once defined, commands, subcommands, aliases, and Diagnose codes cannot
be deleted. They may be altered in various appropriate ways, but they remain
in existence until a SHUTDOWN or RESTART IPL is done.
13. MODIFY COMMAND RESET will not allow a RESET to occur if the resulting
command versions would have different EPNAMEs. This can occur if you
change the EPNAME for a command then add a new version for that
command. To avoid this restriction, you should add new versions of a
command before changing the EPNAMEs associated with the command.
14. The DEFINE COMMAND or DEFINE DIAGNOSE commands should not be
used on a system with an active External Security Manager (ESM);
unpredictable results could occur. To safely define a CP command add the
DEFINE COMMAND or DEFINE DIAGNOSE statement to the SYSTEM
CONFIG file and re-IPL the system. This allows the command and diagnose
additions to control structures to be made prior to activating the ESM.
15. For more information about user-defined commands, see the z/VM: CP Exit
Customization book.
Response 1:
To define a new command, TELL, with:
138 z/VM: CP Commands and Utilities Reference
v 3 versions:
– Privilege class A, IBM class A, issued after logon
– Privilege class B, IBM class B, issued after logon
– Any privilege class, no IBM class, issued before and after logon,
v No minimum abbreviation, and
v The same entry point and syntax as the CP MESSAGE command,
enter the following: