When you create a user-defined workflow variable, you enter an initial value. The Data Integration Service uses the initial value of the variable when the workflow starts. You use a task

Output

tab to assign another value to the variable. After the task completes, the Data Integration Service uses the task output value for the variable during the remainder of the workflow.

For example, you create a workflow variable named CommandStdOutput and set the initial value to "test." In the Command task

Output

tab, you assign the CommandStdOutput workflow variable to the standard output returned by the command. When the workflow starts, the Data Integration Service sets the workflow variable value to "test." If you use the echo command in the Command task to print the value of the CommandStdOutput variable, the Data Integration Service prints the initial value of "test." After the Command task completes, the Data Integration Service sets the workflow variable value to the standard output returned by the command.

You cannot assign task output to system workflow variables.