NXLog User Guide

109.10. External Programs (im_exec)

This module will execute a program or script on startup and read its standard output. It can be used to easily integrate with exotic log sources which can be read only with the help of an external script or program.

Warning

If you are using a Perl script, consider using im_perl instead or turning on Autoflush with $| = 1;, otherwise im_exec might not receive data immediately due to Perl’s internal buffering. See the Perl language reference for more information about $|.

109.10.1. Configuration

The im_exec module accepts the following directives in addition to the common module directives. The Command directive is required.

Command: This mandatory directive specifies the name of the program or script to be executed.

Arg: This is an optional parameter. Arg can be specified multiple times, once for each argument that needs to be passed to the Command. Note that specifying multiple arguments with one Arg directive, with arguments separated by spaces, will not work (the Command would receive it as one argument).

InputType: See the InputType description in the global module configuration section.

Restart: Restart the process if it exits. There is a one second delay before it is restarted to avoid a denial-of-service when a process is not behaving. Looping should be implemented in the script itself, this directive is only to provide some safety against malfunctioning scripts and programs. This boolean directive defaults to FALSE: the Command will not be restarted if it exits.

109.10.2. Examples

Example 547. Emulating im_file

This configuration uses the tail command to read from a file.

Note	The im_file module should be used to read log messages from files. This example only demonstrates the use of the im_exec module.

nxlog.conf


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  <Input messages>
    Module  im_exec
    Command /usr/bin/tail
    Arg     -f
    Arg     /var/log/messages
</Input>

<Output file>
    Module  om_file
    File    "tmp/output"
</Output>

<Route messages_to_file>
    Path    messages => file
</Route>