Timing is everything—even in scripts. You can control the timing in your scripts with such commands as Pause, Sleep, Timeout, Waitfor, and Start. Some of these commands are part of the Windows scripting language; others are from utilities in the Microsoft Windows NT Server 4.0 Resource Kit.
The Pause Command
You can use the Pause command to stop the execution of scripts. This command displays the message Press any key to continue and stops the script’s execution until the user presses a key. For example, if you run the code
Echo Here is the first line of code.
Pause
Echo Here is the second line of code.
you receive the results that Figure 1 shows.
Scriptwriters often use the Pause command to stop a script’s execution so that they can read command output before it scrolls off the screen. However, if a script contains the Pause command, you can’t use Task Scheduler to run that script. (Task Scheduler comes with Microsoft Internet Explorer—IE—4.x and later.) The script will never finish executing because no one is present to press a key to resume the script’s execution. You’ll likely want to use Task Scheduler because it’s easier to use and provides more functionality than the At command and the resource kit’s Winat utility.
The Sleep and Timeout Commands
Although you can’t use the Pause command with Task Scheduler, you can use the resource kit’s Sleep and Timeout utilities. Both utilities let you pause a script for a specified number of seconds. For example, if you want to use the Sleep utility to pause a script for 5 seconds, you can use the command
Sleep 5
Putting this command in the code
Echo Here is the first line of code.
Sleep 5
Echo Here is the second line of code.
prompts the command processor to display the message Here is the first line of code, pause for 5 seconds, then automatically continue to the next line and display the message Here is the second line of code.
Similarly, you can use the Timeout command to pause a script a specified number of seconds. However, the Timeout command differs from the Sleep command in one important respect: Two events can prompt the script to resume running. You can opt to have the script automatically continue executing after the specified number of seconds has elapsed, or you can manually prompt the script to resume before that time is up by pressing a key on the keyboard.
For example, the code
Echo Here is the first line of code.
Timeout 10
Echo Here is the second line of code.
first prompts the command processor to display the message Here is the first line of code. The command processor then pauses until someone presses a key or 10 seconds elapse (whichever comes first), after which it executes the next line of code. Because of this feature, the Timeout utility is ideal for scripts that you plan to execute both manually and as scheduled tasks. The Sleep command is better when you simply need a short delay between two commands or two sections in a script that you plan to run only with Task Scheduler.