builtin - add, delete, or display shell built-ins


builtin [ options ] [pathname ...]


builtin can be used to add, delete, or display built-in commands in the current shell environment. A built-in command executes in the current shell process and can have side effects in the current shell. On most systems, the invocation time for built-in commands is one or two orders of magnitude less than commands that create a separate process.

For each pathname specified, the basename of the pathname determines the name of the built-in. For each basename, the shell looks for a C level function in the current shell whose name is determined by prepending b_ to the built-in name. If pathname contains a /, then the built-in is bound to this pathname. A built-in bound to a pathname will only be executed if pathname is the first executable found during a path search. Otherwise, built-ins are found prior to performing the path search.

If no pathname operands are specified, then builtin displays the current list of built-ins, or just the special built-ins if -s is specified, on standard output. The full pathname for built-ins that are bound to pathnames are displayed.

Libraries containing built-ins can be specified with the -f option. If the library contains a function named lib_init(), this function will be invoked with argument 0 when the library is loaded. The lib_init() function can load built-ins by invoking an appropriate C level function. In this case there is no restriction on the C level function name.

The C level function will be invoked with three arguments. The first two are the same as main() and the third one is a pointer.

builtin cannot be invoked from a restricted shell.


Deletes each of the specified built-ins. Special built-ins cannot be deleted.
-f lib
On systems with dynamic linking, lib names a shared library to load and search for built-ins. Libraries are search for in $PATH and system dependent library directories. The system dependent shared library prefix and/or suffix may be omitted. Once a library is loaded, its symbols become available for the current and subsequent invocations of builtin. Multiple libraries can be specified with separate invocations of builtin. Libraries are searched in the reverse order in which they are specified.
Display only the special built-ins.


All pathname operands and -f options processed successfully.
An error occurred.




builtin (AT&T Research) 1999-07-10
David Korn <dgkorn@gmail.com>
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