SYSTASK

SYSTASK

Executes, lists, or kills asynchronous tasks

Valid: anywhere in a SAS program

OpenVMS specifics: all

Syntax
Details

Syntax

SYSTASK COMMAND "host-command"
<XWAIT|NOXWAIT>
<TASKNAME=taskname>
<MNAME=name-var>
<STATUS=stat-var>

SYSTASK LIST <_ALL_ | taskname> <STATE> <STATVAR>;

SYSTASK KILL taskname <taskname...>;

COMMAND: executes the host-command.
LIST: lists either a specific active task or all of the active tasks in the system.
KILL: forces the termination of the specified task(s).
host-command: specifies the name of an OpenVMS command (including any command-specific options).
XWAIT | NOXWAIT: determines whether SYSTASK COMMAND suspends execution of the current SAS session until the task has completed. NOXWAIT is the default. For tasks that are started with the NOXWAIT option, you can use the WAITFOR statement when necessary to suspend execution of the SAS session until the task has finished.
TASKNAME=taskname: specifies a name that identifies the task. Task names must be unique among all active tasks. A task is active if it is running, or if it has completed and has not been waited for using the WAITFOR statement. Duplicate task names generate an error in the SAS log. If you do not specify a task name, SYSTASK will automatically generate a name. If the task name contains a blank character, enclose the task name in quotes.
MNAME=name-var: specifies a macro variable in which you want SYSTASK to store the task name that it automatically generated for the task. If you specify both the TASKNAME option and the MNAME option, SYSTASK copies the name that you specified with TASKNAME into the variable that you specified with MNAME.
STATUS=stat-var: specifies a macro variable in which you want SYSTASK to store the status of the task. Status variable names must be unique among all active tasks.
_ALL_: specifies all active tasks in the system.
STATE: displays the status of the task, which can be Start, Failed, Running, or Complete.
STATVAR: displays the status variable associated with the task. The status variable is the variable that you assigned with the STATUS option in the SYSTASK COMMAND statement.

Details

SYSTASK allows you to execute host-specific commands from within your SAS session or application. Unlike the X statement, SYSTASK runs these commands as asynchronous tasks, which means that these tasks execute independently of all other tasks that are currently running. Asynchronous tasks run in the background, so you can perform additional tasks while the asynchronous task is still running.

The output from the command is displayed in the SAS log.

Note: Program steps that follow the SYSTASK statements in SAS applications usually depend on the successful execution of the SYSTASK statements. Therefore, syntax errors in some SYSTASK statements will cause your SAS application to abort. [cautionend]

There are two types of tasks that can be run with SYSTASK:

Task: All tasks started with SYSTASK COMMAND are of type Task. For these tasks, if you do not specify STATVAR or STATE, then SYSTASK LIST displays the task name, type, and state, and the name of the status macro variable. You can use SYSTASK KILL to kill only tasks of type Task.
SAS/Connect Process: Tasks started from SAS/Connect with the SYSTASK BEGIN statement are of type SAS/Connect Process. For SAS/Connect processes, SYSTASK LIST displays the task name, type, and state. You cannot use SYSTASK KILL to kill a SAS/Connect process. For information on starting SAS/Connect processes with SYSTASK, refer to SAS/CONNECT User's Guide.

The SYSRC macro variable contains the return code for the SYSTASK statement. The status variable that you specify with the STATUS option contains the return code of the process started with SYSTASK COMMAND. To ensure that a task executes successfully, you should monitor both the status of the SYSTASK statement and the status of the process that is started by the SYSTASK statement.

If a SYSTASK statement cannot execute successfully, the SYSRC macro variable will contain a non-zero value. For example, there could be insufficient resources to complete a task, or the SYSTASK statement could contain syntax errors. With the SYSTASK KILL statement, if one or more of the processes cannot be killed, SYSRC is set to a non-zero value.

When a task is started, its status variable is set to NULL. You can use the status variables for each task to determine which tasks failed to complete. Any task whose status variable is NULL did not complete execution.

Unlike the X statement, you cannot use the SYSTASK statement to start a new interactive session.

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Valid:	anywhere in a SAS program
OpenVMS specifics:	all