More lispref/os.texi small edits
* doc/lispref/os.texi (System Environment): Copyedits. Remove some examples that do not seem useful. Mention setenv third arg. tty-erase-char does not seem to be nil under a window-system. (User Identification): Copyedits. Remove some examples that do not seem useful.
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Glenn Morris
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commit
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2 changed files with 83 additions and 94 deletions
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@ -1,3 +1,11 @@
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2012-03-27 Glenn Morris <rgm@gnu.org>
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* os.texi (System Environment): Copyedits. Remove some examples
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that do not seem useful. Mention setenv third arg.
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tty-erase-char does not seem to be nil under a window-system.
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(User Identification): Copyedits.
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Remove some examples that do not seem useful.
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2012-03-26 Glenn Morris <rgm@gnu.org>
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* os.texi (Startup Summary): Copyedits. Fix startup screen logic.
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@ -833,15 +833,15 @@ system, the user's @acronym{UID}, and so on.
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@defvar system-configuration
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This variable holds the standard GNU configuration name for the
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hardware/software configuration of your system, as a string. The
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convenient way to test parts of this string is with
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@code{string-match}.
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hardware/software configuration of your system, as a string. For
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example, a typical value for a 64-bit GNU/Linux system is
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@samp{"x86_64-unknown-linux-gnu"}.
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@end defvar
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@cindex system type and name
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@defvar system-type
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The value of this variable is a symbol indicating the type of operating
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system Emacs is operating on. Here is a table of the possible values:
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system Emacs is running on. The possible values are:
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@table @code
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@item aix
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@ -861,7 +861,7 @@ The GNU system (using the GNU kernel, which consists of the HURD and Mach).
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@item gnu/linux
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A GNU/Linux system---that is, a variant GNU system, using the Linux
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kernel. (These systems are the ones people often call ``Linux,'' but
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kernel. (These systems are the ones people often call ``Linux'', but
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actually Linux is just the kernel, not the whole system.)
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@item gnu/kfreebsd
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@ -874,33 +874,28 @@ Hewlett-Packard HPUX operating system.
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Silicon Graphics Irix system.
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@item ms-dos
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Microsoft MS-DOS ``operating system.'' Emacs compiled with DJGPP for
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MS-DOS binds @code{system-type} to @code{ms-dos} even when you run it on
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MS-Windows.
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Microsoft's DOS. Emacs compiled with DJGPP for MS-DOS binds
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@code{system-type} to @code{ms-dos} even when you run it on MS-Windows.
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@item usg-unix-v
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AT&T Unix System V.
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@item windows-nt
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Microsoft Windows NT and later. The same executable supports Windows
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9X, but the value of @code{system-type} is @code{windows-nt} in either
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case.
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Microsoft Windows NT, 9X and later. The value of @code{system-type}
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is always @code{windows-nt}, e.g. even on Windows 7.
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@end table
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We do not wish to add new symbols to make finer distinctions unless it
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is absolutely necessary! In fact, we hope to eliminate some of these
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alternatives in the future. We recommend using
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@code{system-configuration} to distinguish between different operating
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systems.
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alternatives in the future. If you need to make a finer distinction
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than @code{system-type} allows for, you can test
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@code{system-configuration}, e.g. against a regexp.
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@end defvar
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@defun system-name
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This function returns the name of the machine you are running on.
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@example
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(system-name)
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@result{} "www.gnu.org"
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@end example
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This function returns the name of the machine you are running on, as a
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string.
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@end defun
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The symbol @code{system-name} is a variable as well as a function. In
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@ -910,6 +905,7 @@ fact, the function returns whatever value the variable
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system. The variable is also useful for constructing frame titles
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(@pxref{Frame Titles}).
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@c FIXME seems like this section is not the best place for this option?
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@defopt mail-host-address
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If this variable is non-@code{nil}, it is used instead of
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@code{system-name} for purposes of generating email addresses. For
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@ -917,37 +913,43 @@ example, it is used when constructing the default value of
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@code{user-mail-address}. @xref{User Identification}. (Since this is
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done when Emacs starts up, the value actually used is the one saved when
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Emacs was dumped. @xref{Building Emacs}.)
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@c FIXME sounds like should probably give this a :set-after and some
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@c custom-initialize-delay voodoo.
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@end defopt
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@deffn Command getenv var &optional frame
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@cindex environment variable access
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This function returns the value of the environment variable @var{var},
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as a string. @var{var} should be a string. If @var{var} is undefined
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in the environment, @code{getenv} returns @code{nil}. If returns
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@samp{""} if @var{var} is set but null. Within Emacs, the environment
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variable values are kept in the Lisp variable @code{process-environment}.
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in the environment, @code{getenv} returns @code{nil}. It returns
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@samp{""} if @var{var} is set but null. Within Emacs, a list of environment
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variables and their values is kept in the variable @code{process-environment}.
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@example
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@group
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(getenv "USER")
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@result{} "lewis"
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@end group
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@end example
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The shell command @code{printenv} prints all or part of the environment:
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@example
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@group
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lewis@@slug[10] % printenv
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PATH=.:/user/lewis/bin:/usr/bin:/usr/local/bin
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bash$ printenv
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PATH=/usr/local/bin:/usr/bin:/bin
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USER=lewis
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@end group
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@group
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TERM=ibmapa16
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SHELL=/bin/csh
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HOME=/user/lewis
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TERM=xterm
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SHELL=/bin/bash
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HOME=/home/lewis
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@end group
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@dots{}
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@end example
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@end deffn
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@c Emacs 19 feature
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@deffn Command setenv variable &optional value
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@deffn Command setenv variable &optional value substitute
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This command sets the value of the environment variable named
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@var{variable} to @var{value}. @var{variable} should be a string.
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Internally, Emacs Lisp can handle any string. However, normally
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@ -955,8 +957,13 @@ Internally, Emacs Lisp can handle any string. However, normally
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of letters, digits and underscores, starting with a letter or
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underscore. Otherwise, errors may occur if subprocesses of Emacs try
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to access the value of @var{variable}. If @var{value} is omitted or
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@code{nil}, @code{setenv} removes @var{variable} from the environment.
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Otherwise, @var{value} should be a string.
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@code{nil} (or, interactively, with a prefix argument), @code{setenv}
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removes @var{variable} from the environment. Otherwise, @var{value}
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should be a string.
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If the optional argument @var{substitute} is non-@code{nil}, Emacs
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calls the function @code{substitute-env-vars} to expand any
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environment variables in @var{value}.
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@code{setenv} works by modifying @code{process-environment}; binding
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that variable with @code{let} is also reasonable practice.
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@ -973,14 +980,14 @@ of this variable.
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@smallexample
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@group
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process-environment
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@result{} ("l=/usr/stanford/lib/gnuemacs/lisp"
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"PATH=.:/user/lewis/bin:/usr/class:/nfsusr/local/bin"
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@result{} ("PATH=/usr/local/bin:/usr/bin:/bin"
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"USER=lewis"
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@end group
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@group
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"TERM=ibmapa16"
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"SHELL=/bin/csh"
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"HOME=/user/lewis")
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"TERM=xterm"
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"SHELL=/bin/bash"
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"HOME=/home/lewis"
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@dots{})
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@end group
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@end smallexample
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@ -991,23 +998,21 @@ specifies the variable, and the other ``duplicates'' are ignored.
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@defvar initial-environment
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This variable holds the list of environment variables Emacs inherited
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from its parent process. It is computed during startup, see
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@ref{Startup Summary}.
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from its parent process when Emacs started.
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@end defvar
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@defvar path-separator
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This variable holds a string which says which character separates
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This variable holds a string that says which character separates
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directories in a search path (as found in an environment variable). Its
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value is @code{":"} for Unix and GNU systems, and @code{";"} for MS-DOS
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and MS-Windows.
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value is @code{":"} for Unix and GNU systems, and @code{";"} for MS systems.
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@end defvar
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@defun parse-colon-path path
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This function takes a search path string such as would be the value of
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This function takes a search path string such as the value of
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the @code{PATH} environment variable, and splits it at the separators,
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returning a list of directory names. @code{nil} in this list stands for
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``use the current directory.'' Although the function's name says
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``colon,'' it actually uses the value of @code{path-separator}.
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returning a list of directory names. @code{nil} in this list means
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the current directory. Although the function's name says
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``colon'', it actually uses the value of @code{path-separator}.
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@example
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(parse-colon-path ":/foo:/bar")
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@ -1022,30 +1027,32 @@ value is a string, and does not include a directory name.
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@defvar invocation-directory
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This variable holds the directory from which the Emacs executable was
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invoked, or perhaps @code{nil} if that directory cannot be determined.
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invoked, or @code{nil} if that directory cannot be determined.
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@end defvar
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@defvar installation-directory
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If non-@code{nil}, this is a directory within which to look for the
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@file{lib-src} and @file{etc} subdirectories. This is non-@code{nil}
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@file{lib-src} and @file{etc} subdirectories. In an installed Emacs,
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it is normally @code{nil}. It is non-@code{nil}
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when Emacs can't find those directories in their standard installed
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locations, but can find them in a directory related somehow to the one
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containing the Emacs executable.
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containing the Emacs executable (i.e., @code{invocation-directory}).
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@end defvar
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@defun load-average &optional use-float
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This function returns the current 1-minute, 5-minute, and 15-minute load
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averages, in a list.
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This function returns the current 1-minute, 5-minute, and 15-minute
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system load averages, in a list. The load average indicates the
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number of processes trying to run on the system.
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By default, the values are integers that are 100 times the system load
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averages, which indicate the average number of processes trying to run.
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If @var{use-float} is non-@code{nil}, then they are returned
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as floating point numbers and without multiplying by 100.
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averages, but if @var{use-float} is non-@code{nil}, then they are
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returned as floating point numbers without multiplying by 100.
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If it is impossible to obtain the load average, this function signals
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an error. On some platforms, access to load averages requires
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installing Emacs as setuid or setgid so that it can read kernel
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information, and that usually isn't advisable.
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@c FIXME which platforms are these? Are they still relevant?
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If the 1-minute load average is available, but the 5- or 15-minute
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averages are not, this function returns a shortened list containing
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@ -1060,13 +1067,9 @@ the available averages.
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(load-average t)
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@result{} (1.69 0.48 0.36)
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@end group
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@group
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lewis@@rocky[5] % uptime
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11:55am up 1 day, 19:37, 3 users,
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load average: 1.69, 0.48, 0.36
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@end group
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@end example
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The shell command @code{uptime} returns similar information.
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@end defun
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@defun emacs-pid
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@ -1077,7 +1080,8 @@ as an integer.
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@defvar tty-erase-char
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This variable holds the erase character that was selected
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in the system's terminal driver, before Emacs was started.
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The value is @code{nil} if Emacs is running under a window system.
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@c FIXME? Seems untrue since 23.1. For me, it is 0.
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@c The value is @code{nil} if Emacs is running under a window system.
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@end defvar
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@node User Identification
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@ -1107,27 +1111,18 @@ want to use the default value.
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@end defopt
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@defun user-login-name &optional uid
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If you don't specify @var{uid}, this function returns the name under
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which the user is logged in. If the environment variable @code{LOGNAME}
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is set, that value is used. Otherwise, if the environment variable
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@code{USER} is set, that value is used. Otherwise, the value is based
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on the effective @acronym{UID}, not the real @acronym{UID}.
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This function returns the name under which the user is logged in.
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It uses the environment variables @code{LOGNAME} or @code{USER} if
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either is set. Otherwise, the value is based on the effective
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@acronym{UID}, not the real @acronym{UID}.
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If you specify @var{uid}, the value is the user name that corresponds
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to @var{uid} (which should be an integer), or @code{nil} if there is
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no such user.
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@example
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@group
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(user-login-name)
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@result{} "lewis"
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@end group
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@end example
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If you specify @var{uid} (a number), the result is the user name that
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corresponds to @var{uid}, or @code{nil} if there is no such user.
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@end defun
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@defun user-real-login-name
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This function returns the user name corresponding to Emacs's real
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@acronym{UID}. This ignores the effective @acronym{UID} and ignores the
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@acronym{UID}. This ignores the effective @acronym{UID}, and the
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environment variables @code{LOGNAME} and @code{USER}.
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@end defun
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@ -1135,16 +1130,8 @@ environment variables @code{LOGNAME} and @code{USER}.
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This function returns the full name of the logged-in user---or the value
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of the environment variable @code{NAME}, if that is set.
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@c "Bil" is the correct spelling.
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@example
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@group
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(user-full-name)
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@result{} "Bil Lewis"
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@end group
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@end example
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If the Emacs job's user-id does not correspond to any known user (and
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provided @code{NAME} is not set), the value is @code{"unknown"}.
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If the Emacs process's user-id does not correspond to any known user (and
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provided @code{NAME} is not set), the result is @code{"unknown"}.
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If @var{uid} is non-@code{nil}, then it should be a number (a user-id)
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or a string (a login name). Then @code{user-full-name} returns the full
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@ -1164,14 +1151,8 @@ Titles}).
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@defun user-real-uid
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This function returns the real @acronym{UID} of the user.
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The value may be a floating point number.
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@example
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@group
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(user-real-uid)
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@result{} 19
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@end group
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@end example
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The value may be a floating point number, in the (unlikely) event that
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the UID is too large to fit in a Lisp integer.
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@end defun
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@defun user-uid
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