Info Catalog elisp: Terminal-Specific elisp: Starting Up

elisp: Command-Line Arguments

 
 38.1.4 Command-Line Arguments
 -----------------------------
 
 You can use command-line arguments to request various actions when you
 start Emacs.  Note that the recommended way of using Emacs is to start
 it just once, after logging in, and then do all editing in the same
 Emacs session ((emacs)Entering Emacs).  For this reason, you
 might not use command-line arguments very often; nonetheless, they can
 be useful when invoking Emacs from session scripts or debugging Emacs.
 This section describes how Emacs processes command-line arguments.
 
  -- Function: command-line
      This function parses the command line that Emacs was called with,
      processes it, and (amongst other things) loads the user’s init file
      and displays the startup messages.
 
  -- Variable: command-line-processed
      The value of this variable is ‘t’ once the command line has been
      processed.
 
      If you redump Emacs by calling ‘dump-emacs’ (Building
      Emacs), you may wish to set this variable to ‘nil’ first in order
      to cause the new dumped Emacs to process its new command-line
      arguments.
 
  -- Variable: command-switch-alist
      This variable is an alist of user-defined command-line options and
      associated handler functions.  By default it is empty, but you can
      add elements if you wish.
 
      A “command-line option” is an argument on the command line, which
      has the form:
 
           -OPTION
 
      The elements of the ‘command-switch-alist’ look like this:
 
           (OPTION . HANDLER-FUNCTION)
 
      The CAR, OPTION, is a string, the name of a command-line option
      (not including the initial hyphen).  The HANDLER-FUNCTION is called
      to handle OPTION, and receives the option name as its sole
      argument.
 
      In some cases, the option is followed in the command line by an
      argument.  In these cases, the HANDLER-FUNCTION can find all the
      remaining command-line arguments in the variable
      ‘command-line-args-left’ (see below).  (The entire list of
      command-line arguments is in ‘command-line-args’.)
 
      The command-line arguments are parsed by the ‘command-line-1’
      function in the ‘startup.el’ file.  See also Command Line
      Arguments for Emacs Invocation (emacs)Emacs Invocation.
 
  -- Variable: command-line-args
      The value of this variable is the list of command-line arguments
      passed to Emacs.
 
  -- Variable: command-line-args-left
      The value of this variable is the list of command-line arguments
      that have not yet been processed.
 
  -- Variable: command-line-functions
      This variable’s value is a list of functions for handling an
      unrecognized command-line argument.  Each time the next argument to
      be processed has no special meaning, the functions in this list are
      called, in order of appearance, until one of them returns a
      non-‘nil’ value.
 
      These functions are called with no arguments.  They can access the
      command-line argument under consideration through the variable
      ‘argi’, which is bound temporarily at this point.  The remaining
      arguments (not including the current one) are in the variable
      ‘command-line-args-left’.
 
      When a function recognizes and processes the argument in ‘argi’, it
      should return a non-‘nil’ value to say it has dealt with that
      argument.  If it has also dealt with some of the following
      arguments, it can indicate that by deleting them from
      ‘command-line-args-left’.
 
      If all of these functions return ‘nil’, then the argument is
      treated as a file name to visit.
 

Info Catalog elisp: Terminal-Specific elisp: Starting Up