Exit Keyword

Exit= filename

This keyword is not available in LISTSERV Lite.

An "exit" is a program supplied by the customer to modify the behavior of a product (such as LISTSERV) in ways that the supplier of the product does not support through standard options. The product checks for the presence of the exit program and calls it on a number of occasions, called "exit points". In some cases, the exit program supplies an answer ("return code") to the main program, which adjusts its behavior accordingly. For instance, LISTSERV may ask an exit program "Is it OK to add joe@example.com to the ABC-L list?", and the program will answer "yes" or "no", and possibly send a message to the user explaining why his subscription was accepted or rejected. In other cases, the exit point call is purely informative. The exit program gets a chance to do something, such as sending an informational message to a user but does not return any answer. Because this exit is a computer program, it must be prepared and installed by the LISTSERV administrator.

List exits allow you to control the major events associated with list maintenance. This makes it easier to tailor the behavior of LISTSERV to local requirements that are too specific to be addressed through standard facilities.

An exit is enabled by adding "Exit= filename" to the list header. For security reasons, all exits must be explicitly declared in the LIST_EXITS site configuration variable. This prevents list owners from causing the invocation of arbitrary executable files through the use of the "Exit=" keyword.

This keyword is not usable by list owners without specific intervention by the LISTSERV administrator. For more information, see the LISTSERV Advanced Topics Manual.