SystemExecute

Short Description
Ports
Metadata
SystemExecute Attributes
Details
Examples
Best Practices
See also

Short Description

SystemExecute executes system commands.

ComponentSame input metadataSorted inputsInputsOutputsEach to all outputs[1]JavaCTLAuto-propagated metadata
SystemExecute-
no
0-10-1-
no
no
no

[1]  Component sends each data record to all connected output ports.

Ports

Port typeNumberRequiredDescriptionMetadata
Input0
no
For standard input of the specified system command (input of the process)Any1
Output0[1]For a standard output of the specified system command (output of the process)Any2

[1]  A standard output must be written to an output port or output file. If both an output port is connected and output file is specified, an output is sent to output port only.

Metadata

SystemExecute does not propagate metadata.

SystemExecute has no metadata template.

SystemExecute Attributes

AttributeReqDescriptionPossible values
Basic
System commandyes

A command to be executed by the system. The command is always saved to a tmp file as a script. In case an interpreter is specified, it executes that script. If the command requires an input, it has to be sent to the command through the optional input port. For details, see How it works.

 
Process input/output charset 

Encoding used for formatting/parsing data for input/from output of system process.

The default encoding depends on DEFAULT_CHARSET_DECODER in defaultProperties.

UTF-8 | <any other>
Output file URL[1]

Name of a file, including the path, to which output of the process (together with errors) should be written if the output edge is not connected and if System command creates the standard output. For more information, see URL File Dialog.

 
Append 

By default, the contents of an output file is always deleted and overwritten by new data. If set to true, new output data is appended to the output file without deleting the file contents.

false (default) | true
Command interpreter 

An interpreter that should execute the command. If specified, System command is saved as a script to a temporary file and executed by this interpreter. Its form must be the following: <interpreter name> [parameters] ${} [parameters]. If an interpreter is defined, System command is saved to a temporary file and executed as a script. In such a case, the component replaces this ${} expression by the name of this temporary script file.

See the list of well known interprets.

 
Working directory A working directory of the component.current directory[2] (default) | other directory
Advanced
Number of error lines The number of lines that are printed if a command finishes with errors.2 (default) | 1-N
Environment 

System-dependent mapping from variables to values. Mappings are separated by a colon, semicolon or pipe. By default, the new value is appended to the environment of the current process. Both PATH=/home/user/mydir and PATH=/home/user/mydir!true means that /home/user/mydir will be appended to the existing PATH. Whereas PATH=/home/user/mydir!false replaces the old PATH value by the new one (/home/user/mydir).

For example: PATH=/home/user/mydir[!true] (default) | PATH=/home/user/mydir!false

Timeout for producer/consumer workers (ms) 

Timeout; by default in milliseconds, but other time units may be used. For details, see Timeout.

0 (without limitation) | 1-n
Ignore exit value 

In case the executed system command returns non-zero value, the component fails. This option can change this behavior, the exit value can be ignored.

true | false (default)

[1]  If the output port is not connected, a standard output can only be written to a specified output file. If the output port is connected, an output file will not be created and a standard output will be sent to the output port.

[2]  A working directory defaults to current process working directory only if the graph runs on a local CloverDX engine. If it runs on the CloverDX Server, then the default working directory is the sandbox root. In case of a clustered Server environment, the default working directory is the sandbox root only if the sandbox is of a "shared" type, or it is of a "local" type and is located on the node running the SystemExecute component. Otherwise the Server node cannot access the sandbox locally, i.e. the sandbox is of type "local" but is located on a remote node, in which case the working directory defaults to some arbitrary temporary directory supplied by the Temp Space Management subsystem of the Server node. The component prints a message about which working directory was actually used into a graph run log at INFO log level.

Details

SystemExecute executes commands and arguments specified in the component itself as a separate process. The commands receive a standard input through the input port and send a standard output to the output port (if the command creates any output).

How it works

SystemExecute runs the command specified in the System command and creates two threads.

  • The first thread (producer) reads records from the input edge, serializes them and sends them to stdin of the command.

  • The second thread (consumer) reads stdout of the command, parses it and sends it to the output edge.

Timeout

  • When the command ends, the component still waits until both the producer and the consumer also finish their work. The time is defined in the Timeout attribute.

  • By default, timeout is unlimited now. In case of an unexpected deadlock, you can set the timeout to any number of milliseconds.

Well known command interprets

The following list contains possible interprets that can be used in SystemExecute component. You are not limited to the items from this list.

Windows
  • cmd /c ${}

  • powershell ${}

Linux
  • /bin/sh ${}

  • /bin/bash ${}

  • /bin/tcsh ${}

  • /usr/bin/perl ${}

  • /usr/bin/python ${}

Difference between SystemExecute and ExecuteScript

SystemExecute uses a data-oriented approach. It allows you to stream data from and to a script.

ExecuteScript executes scripts in steps. It allows you to receive scripts from an input edge and execute them one by one.

Examples

Run command on Linux
Run command on Windows
Run command that saves its output to file
Calling external filter

Run command on Linux

This example shows execution of command on Linux using SystemExecute.

Run the uptime command using the SystemExecute component. Send the results through an edge to the next component.

Solution

Connect the output port of SystemExecute with the next component. Metadata of the edge should contain just one string field.

Configure SystemExecute.

AttributeValue
System commanduptime
Command interpreter/bin/bash ${}

Run command on Windows

This example shows execution of command on MS Windows using SystemExecute

Run tasklist using SystemExecute component. Send the results trough an edge to the next component.

Solution

Connect the output port of SystemExecute with the next component. Metadata of the edge should contain just one string field.

Configure SystemExecute.

AttributeValue
System commandtasklist
Process input/output charsetwindows-1252
Command interpretercmd /c ${}
[Note]Note

If process input/output charset is not set or it is set incorrectly, you can encounter the following error message in the graph log: Character decoding error occurred. Set correct charset. Current charset is UTF-8.

Run command that saves its output to file

This example shows way to run command with SystemExecute and save the output from the command to a file.

Run command who and save its output to the file logged_users.txt for further processing.

Solution

AttributeValue
System commandwho
Output file URL${DATAOUT_DIR}/logged_users.txt
Command interpreter/bin/bash ${}

Calling external filter

This example shows way to use an external shell filter from SystemExecute: the data from graph is sent to input stream of the filter and the output of the script is sent back to the graph.

Call sed to replace A with B.

Solution

Connect input port of SystemExecute with component producing data and output port of SystemExecute with component consuming data. Assign metadata to the edges. Metadata on both edges should be the same, unless the script changes the number of columns or delimiters.

AttributeValue
System commandsed 's_A_B_g'
Command interpreter/bin/bash ${}

Best Practices

We recommend users to explicitly specify Process input/output charset.

See also

ExecuteScript
Common Properties of Components
Specific Attribute Types
Others Comparison