Process Module

This XQuery Module provides functions for executing system commands from XQuery.

Conventions

All functions in this module are assigned to the http://basex.org/modules/proc namespace, which is statically bound to the proc prefix.
All errors are assigned to the http://basex.org/errors namespace, which is statically bound to the bxerr prefix.

Functions

proc:system

Signatures	proc:system($cmd as xs:string) as xs:string proc:system($cmd as xs:string, $args as xs:string*) as xs:string proc:system($cmd as xs:string, $args as xs:string*, $options as map(xs:string, xs:string)) as xs:string
Summary	Executes the specified command in a separate process and returns the result as string. $cmd is the name of the command, arguments to the command may be specified via $args. The $options parameter contains process options: encoding: convert result to the specified encoding. If no encoding is supplied, the system’s default encoding is used. timeout: abort process execution after the specified number of seconds. dir: process command in the specified directory.
Errors	BXPRnnnn: If the command results in an error, an XQuery error will be raised. Its code will consist of the letters BXPR and four digits with the command’s exit code. BXPR9999: the specified encoding does not exist or is not supported.
Examples	proc:system('date') returns the current date on a Linux system. The following example returns "Command not found", if the command "xyz" cannot be located or executed: try { proc:system('xyz') } catch bxerr:BXPR0002 { 'Command not found.' }

proc:execute

Template:Mark encoding option moved to options argument, timeout and dir options added.

Signatures	proc:execute($cmd as xs:string) as element(result) proc:execute($cmd as xs:string, $args as xs:string*) as element(result) proc:execute($cmd as xs:string, $args as xs:string*, $options as map(xs:string, xs:string)) as element(result)
Summary	Executes the specified command in a separate process and returns the result as element. $cmd is the name of the command, and arguments to the command may be specified via $args. The same $options are allowed as for proc:system. A result has the following structure: <result> <output>...result output...</output> <error>...error output...</error> <code>0</code> </result>
Errors	BXPR9999: the specified encoding does not exist or is not supported.
Examples	proc:execute('dir', '\') returns the files of the root directory of a Windows system. proc:execute('ls', ('-l', '-a')) executes the ls -la command on Unix systems.

proc:fork

Signatures	proc:fork($cmd as xs:string) as element(result) proc:fork($cmd as xs:string, $args as xs:string*) as element(result) proc:fork($cmd as xs:string, $args as xs:string*, $options as map(xs:string, xs:string)) as element(result)
Summary	Executes the specified command and ignores the result. $cmd is the name of the command, and arguments to the command may be specified via $args. The same $options are allowed as for proc:system (but the encoding will be ignored).
Errors	BXPR9999: the specified encoding does not exist or is not supported.
Examples	proc:fork('sleep', '5'): sleep for 5 seconds (no one should notice).

proc:property

Signatures	proc:property($name as xs:string) as xs:string?
Summary	Returns the system property, specified by $name, or a context parameter of the web.xml file with that name (see Web Applications). An empty sequence is returned if the property does not exist. For environment variables of the operating system, please use fn:environment-variable.
Examples	map:merge(proc:property-names() ! map:entry(., proc:property(.))) returns a map with all system properties.

proc:property-names

Signatures	proc:property-names() as xs:string*
Summary	Returns the names of all Java system properties and context parameters of the web.xml file (see Web Applications). For environment variables of the operating system, please use fn:available-environment-variables.
Examples	proc:property('java.runtime.version') returns the version of the Java runtime engine.

Errors

Code	Description
BXPR9999	The specified encoding does not exist or is not supported.

Changelog

Version 9.0

• Added: proc:fork

Version 8.6

• Updated: proc:system, proc:exec: encoding option moved to options argument, timeout and dir options added.

Version 8.3

• Added: proc:property, proc:property-names.

The module was introduced with Version 7.3.