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*, $encoding as 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 result can be explicitly converted to a specified $encoding. If no encoding is specified, the system’s default encoding is used.
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

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*, $encoding as 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. Arguments to the command may be specified via $args. The result can be explicitly converted to a specified $encoding. If no encoding is specified, the system’s default encoding is used. 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:property

Signatures	proc:property($name as xs:string) as xs:string?
Summary	Returns the Java system property specified by $name. 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. 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 8.3

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

The module was introduced with Version 7.3.