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Apache HTTP Server Version 2.0

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Apache Module mod_cgid

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Description:Execution of CGI scripts using an external CGI daemon
Status:Base
Module Identifier:cgid_module
Source File:mod_cgid.c
Compatibility:Unix threaded MPMs only

Summary

Except for the optimizations and the additional ScriptSock directive noted below, mod_cgid behaves similarly to mod_cgi. See the mod_cgi summary for additional details about Apache and CGI.

On certain unix operating systems, forking a process from a multi-threaded server is a very expensive operation because the new process will replicate all the threads of the parent process. In order to avoid incurring this expense on each CGI invocation, mod_cgid creates an external daemon that is responsible for forking child processes to run CGI scripts. The main server communicates with this daemon using a unix domain socket.

This module is used by default instead of mod_cgi whenever a multi-threaded MPM is selected during the compilation process. At the user level, this module is identical in configuration and operation to mod_cgi. The only exception is the additional directive ScriptSock which gives the name of the socket to use for communication with the cgi daemon.

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Compatibility with 1.3.x

mod_cgid treats consecutive plus signs in a query string as a single plus sign, discarding the empty command-line arguments, as the latest candidate RFC for CGI disallows URLs with consecutive plus signs.

This is a change from the behavior in version 1.3.x. To allow changing this behavior, mod_cgid has been modified to respect a startup-time environment variable, IHS_CGID_PASS_NULL_ISINDEX_ARGUMENTS.

When this variable is set to any value, mod_cgid will pass a null command line argument for each pair of consecutive '+' characters in the query string. This behavior matches the behavior of IHS 1.3.x.

Example

          Example values in <ihsinst>/bin/envvars:</ihsinst>
          IHS_CGID_PASS_NULL_ISINDEX_ARGUMENTS=1
          export IHS_CGID_PASS_NULL_ISINDEX_ARGUMENTS

          Example ISINDEX CGI URL:
          http://example.com/cgi-bin/echoargs.cgi?a++b+c++d

          Default behavior without IHS_CGID_PASS_NULL_ISINDEX_ARGUMENTS:
          $1 = "a"
          $2 = "b"
          $3 = "c"

          Behavior with IHS_CGID_PASS_NULL_ISINDEX_ARGUMENTS:
          $1 = "a"
          $2 = ""
          $3 = "b"
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ScriptSock Directive

Description:The name of the socket to use for communication with the cgi daemon
Syntax:ScriptSock file-path
Default:ScriptSock logs/cgisock
Context:server config
Status:Base
Module:mod_cgid

This directive sets the name of the socket to use for communication with the CGI daemon. The socket will be opened using the permissions of the user who starts Apache (usually root). To maintain the security of communications with CGI scripts, it is important that no other user has permission to write in the directory where the socket is located.

Example

ScriptSock /var/run/cgid.sock

Available Languages:  en