In this section, we will explore various system management commands in Control Language (CL). These commands are essential for managing and maintaining the system's overall health and performance. By the end of this module, you will be able to perform system management tasks such as managing system values, controlling system status, and handling system messages.

1. System Values: Parameters that control the behavior of the system.
2. System Status: Information about the current state of the system.
3. System Messages: Notifications and alerts generated by the system.
4. System Control: Commands to start, stop, and manage system operations.

The DSPSYSVAL command is used to display the current values of system parameters.

Syntax:

Example:

This command displays the current system time.

The CHGSYSVAL command is used to change the values of system parameters.

Syntax:

Example:

This command changes the system time to 12:00:00.

The DSPSTS command provides information about the current status of the system, including CPU usage, memory usage, and job status.

Syntax:

Example:

This command displays the system status.

The WRKSYSSTS command allows you to interactively work with the system status, providing a more detailed view and additional options for managing system resources.

Syntax:

Example:

This command opens an interactive session to work with the system status.

The DSPMSG command displays messages that have been sent to the system operator message queue.

Syntax:

Example:

This command displays messages in the system operator message queue.

The SNDMSG command is used to send a message to a specified message queue.

Syntax:

Example:

This command sends a message to the system operator.

The ENDSBS command is used to end a subsystem or the entire system.

Syntax:

Example:

This command immediately ends the interactive subsystem.

The STRSBS command is used to start a subsystem.

Syntax:

Example:

This command starts the interactive subsystem.

1. Display the current system date.

   DSPSYSVAL SYSVAL(QDATE)
   

2. Change the system date to '2023-12-31'.

   CHGSYSVAL SYSVAL(QDATE) VALUE('2023-12-31')
   

1. Display the current system status.

   DSPSTS
   

2. Open an interactive session to work with the system status.

   WRKSYSSTS
   

1. Send a message to the system operator.

   SNDMSG MSG('System backup completed successfully') TOUSR(QSYSOPR)
   

2. Display the messages in the system operator message queue.

   DSPMSG MSGQ(QSYSOPR)
   

• Incorrect System Value Names: Ensure you use the correct system value names when using DSPSYSVAL and CHGSYSVAL commands.
• Immediate vs. Delayed Actions: When ending subsystems, be cautious with the OPTION(*IMMED) parameter as it forces an immediate end, which might disrupt ongoing processes.
• Message Queue Names: Verify the message queue names when using DSPMSG and SNDMSG commands to avoid sending messages to the wrong queue.

In this section, we covered essential system management commands in CL, including displaying and changing system values, working with system status, and handling system messages. These commands are crucial for maintaining the system's health and ensuring smooth operations. Practice these commands to become proficient in managing your system effectively.

Next, we will delve into Module 3: Variables and Expressions, where we will explore how to define and use variables, work with expressions, and manipulate strings in CL.