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System Exec

LabVIEW 8.5 Help
August 2007

NI Part Number:
371361D-01

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Executes a system command. Use the System Exec VI to execute or launch other Windows applications or Linux command-line applications from within VIs. With the System Exec VI, you execute a system-level command line that can include any parameters supported by the application you want to launch.

Details  Example

Use expected output size to improve memory efficiency. Use a number slightly larger than the output size you expect. The command runs if you exceed this size, but LabVIEW uses its memory less efficiently. The default is 4096.
If wait until completion? is TRUE, standard input is available as input to the command and standard output and standard error are available when the command finishes running. If FALSE, the command runs in the background and its input and output are not available.
command line indicates the command LabVIEW calls to run a program. If the executable is not in a directory listed in the PATH environment variable, the command line must contain the full path to the executable. (Windows) To use a DOS command, insert cmd /c before the command.
standard input is the text to pass to the command line as standard input.
working directory is the file system directory from which you want to execute the command. You do not have to set working directory.
Note  Do not use working directory to locate the executable you want to run. working directory applies to the executable only after it launches.
error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.
status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
If run minimized? is TRUE, the VI minimizes the run of your executable program. The default is FALSE. run minimized? is unused on Linux platforms.
standard output returns information from the program you called if wait until completion is TRUE. If wait until completion is FALSE, System Exec returns an empty string.
standard error returns errors from the program you called if wait until completion is TRUE. If wait until completion is FALSE, System Exec returns an empty string.
return code indicates the system-dependent exit code that the command returns.
error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error.
status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

System Exec Details

(Mac OS and Linux) You can use wildcards and shell meta-characters. (Linux) You can use pipes.

To launch an executable with options using the syntax filename.exe -option1 -option2, create a filename.bat file that calls the executable with the options syntax and use this VI to call the filename.bat file.

Example

Refer to the Calling System Exec VI in the labview\examples\comm directory for an example of using the System Exec VI.


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