Escapes to the current operating system and
executes an operating system command.
Syntax
OS-COMMAND
[ SILENT | NO-WAIT | NO-CONSOLE ]
[ command-token | VALUE ( expression ) ]...
|
- SILENT
- After processing an operating system command, the AVM shell pauses.
To exit the window in Windows GUI platforms, you must type exit.
To exit the window in Windows character platforms, you must type exit and
press RETURN or SPACEBAR. You can use the SILENT option
to eliminate this pause. Use this option only if you are sure that
the program, command, or batch file does not generate any output
to the screen. Cannot be used with NO-WAIT.
- NO-WAIT
- In a multi-tasking environment, causes the AVM to immediately pass
control back to next statement after the OS-COMMAND without waiting
for the operating system command to terminate. Cannot be used with
SILENT. This option is supported in Windows only.
- NO-CONSOLE
- While processing an operating system command, the AVM creates a
console window. The console window may not be cleaned up after the command
is executed. You can use the NO-CONSOLE option to prevent this window
from being created in the first place.
-
command-token
| VALUE
( expression )
- One or more command words and symbols that you want to pass
the operating system to execute. The VALUE option generates the
command tokens included in expression, a character
string expression. The specified combination of command-token and
VALUE(expression) options can form any legal
combination of commands and command options permitted by the operating
system. These can contain Unicode characters. See OpenEdge
Development: Internationalizing Applications for more information
about Unicode.
Example
There
are two principal uses for the OS-COMMAND statement: to execute a
utility that has the same syntax on two or more different operating
systems, and to execute an operating system statement input by a
user.
In both instances, the OS-COMMAND statement eliminates
the need to use the OPSYS statement to determine the operating system
and then use conditional logic to execute the appropriate code.
The OS-COMMAND statement, therefore, makes an application more portable.
This
procedure prompts the user for an operating system command and then
uses the OS-COMMAND statement to execute the command:
r-os-com.p
DEFINE VARIABLE comm-line AS CHARACTER NO-UNDO FORMAT "x(70)".
REPEAT:
UPDATE comm-line.
OS-COMMAND VALUE(comm-line).
END.
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Notes
- If
you want to run an operating system internal command, such as Windows dir,
do not use the NO-WAIT keyword. The results are unpredictable.
- If you want to run an application that requires Windows, you
must use the NO-WAIT option.
- The NO-WAIT option is unavailable in environments that are not multi-tasking.
- The OS-COMMAND statement always sets the value for the OS-ERROR
function to 0, whether or not an error occurs. Thus, an operating
system error is never returned for the OS-COMMAND statement.
