LOADER.4TH(8)              BSD System Manager's Manual             LOADER.4TH(8)

     loader.4th — loader.conf processing tools

     The file that goes by the name of loader.4th is a set of commands designed
     to manipulate loader.conf(5) files.  The default /boot/loader.rc includes
     loader.4th and uses one of its commands to automatically read and process
     the standard loader.conf(5) files.  Other commands exists to help the user
     specify alternate configurations.

     The commands of loader.4th by themselves are not enough for most uses.
     Please refer to the examples below for the most common situations, and to
     loader(8) for additional commands.

     Before using any of the commands provided in loader.4th, it must be
     included through the command:

           include loader.4th

     This line is present in the default /boot/loader.rc file, so it is not
     needed (and should not be re-issued) in a normal setup.

     The commands provided by it are:
           boot kernelname [...]
           boot directory [...]
           boot -flag ...         Boot as specified by the loader.conf(5) files

                                  Depending on the arguments passed, it can
                                  override boot flags and either the kernel name
                                  or the search path for kernel and modules.

           boot-conf kernelname [...]
           boot-conf directory [...]
           boot-conf -flag ...    Works like boot described above, but instead
                                  of booting immediately, uses autoboot, so it
                                  can be stopped.

           start                  Reads /boot/defaults/loader.conf, all other
                                  loader.conf(5) files specified in it, then
                                  loads the desired kernel and modules (if not
                                  already loaded).  After which you can use the
                                  boot or autoboot commmands or simply exit
                                  (provided autoboot_delay is not set to NO) to
                                  boot the system.  start is the command used in
                                  the default /boot/loader.rc file (see

           initialize             Initialize the support library so commands can
                                  be used without executing start first.  Like
                                  start, it reads /boot/defaults/loader.conf and
                                  all other loader.conf(5) files specified in it
                                  (but does not load kernel or modules).
                                  Returns a flag on the stack to indicate if any
                                  configuration files were successfully loaded.

           read-conf filename     Reads and processes a loader.conf(5) file.
                                  Does not proceed to boot.

           enable-module module   Enables the loading of module.

           disable-module module  Disables the loading of module.

           toggle-module module   Toggles the loading of module on and off.

           show-module module     Shows the information gathered in the
                                  loader.conf(5) files about the module module.

           retry                  Used inside loader.conf(5) files to specify
                                  the action after a module loading fails.

           ignore                 Used inside loader.conf(5) files to specify
                                  the action after a module loading fails.
           try-include file [file ...]
                                  Process script files if they exist.  Each
                                  file, in turn, is completely read into memory,
                                  and then each of its lines is passed to the
                                  command line interpreter.  If any error is
                                  returned by the interpreter, the try-include
                                  command aborts immediately, without reading
                                  any other files, and silently returns without

     /boot/loader      The loader(8).
     /boot/loader.4th  loader.4th itself.
     /boot/loader.rc   loader(8) bootstrapping script.
                       File loaded by the start command.

     Standard /boot/loader.rc:

           include /boot/loader.4th

     Load a different kernel with the standard configuration:

           set kernel="kernel.old"

     Read an additional configuration file and then proceed to boot:

           read-conf /boot/special.conf

     Disable the loading of the splash screen module and bitmap and then proceed
     to boot:

           disable-module splash_bmp
           disable-module bitmap

     loader.conf(5), loader(8)

     The loader.4th set of commands first appeared in FreeBSD 3.2.

     The loader.4th set of commands was written by Daniel C. Sobral

     A British espionage series.

BSD                             November 13, 2013                            BSD