Emacs provides access to variables in the operating system environment through various functions. These variables include the name of the system, the user's UID, and so on.
This variable holds the standard GNU configuration name for the hardware/software configuration of your system, as a string. The convenient way to test parts of this string is with
The value of this variable is a symbol indicating the type of operating system Emacs is operating on. Here is a table of the possible values:
- IBM's AIX.
- Berkeley BSD and its variants.
- Cygwin, a Posix layer on top of MS-Windows.
- Darwin (Mac OS X).
- The GNU system (using the GNU kernel, which consists of the HURD and Mach).
- A GNU/Linux system—that is, a variant GNU system, using the Linux kernel. (These systems are the ones people often call “Linux,” but actually Linux is just the kernel, not the whole system.)
- A GNU (glibc-based) system with a FreeBSD kernel.
- Hewlett-Packard HPUX operating system.
- Silicon Graphics Irix system.
- Microsoft MS-DOS “operating system.” Emacs compiled with DJGPP for MS-DOS binds
ms-doseven when you run it on MS-Windows.
- AT＆T Unix System V.
- Microsoft Windows NT and later. The same executable supports Windows 9X, but the value of
windows-ntin either case.
We do not wish to add new symbols to make finer distinctions unless it is absolutely necessary! In fact, we hope to eliminate some of these alternatives in the future. We recommend using
system-configurationto distinguish between different operating systems.
This function returns the name of the machine you are running on.(system-name) ⇒ "www.gnu.org"
system-name is a variable as well as a function. In
fact, the function returns whatever value the variable
system-name currently holds. Thus, you can set the variable
system-name in case Emacs is confused about the name of your
system. The variable is also useful for constructing frame titles
(see Frame Titles).
If this variable is non-
nil, it is used instead of
system-namefor purposes of generating email addresses. For example, it is used when constructing the default value of
user-mail-address. See User Identification. (Since this is done when Emacs starts up, the value actually used is the one saved when Emacs was dumped. See Building Emacs.)
This function returns the value of the environment variable var, as a string. var should be a string. If var is undefined in the environment,
nil. If returns ‘""’ if var is set but null. Within Emacs, the environment variable values are kept in the Lisp variable
process-environment.(getenv "USER") ⇒ "lewis" lewis@slug % printenv PATH=.:/user/lewis/bin:/usr/bin:/usr/local/bin USER=lewis TERM=ibmapa16 SHELL=/bin/csh HOME=/user/lewis
This command sets the value of the environment variable named variable to value. variable should be a string. Internally, Emacs Lisp can handle any string. However, normally variable should be a valid shell identifier, that is, a sequence of letters, digits and underscores, starting with a letter or underscore. Otherwise, errors may occur if subprocesses of Emacs try to access the value of variable. If value is omitted or
setenvremoves variable from the environment. Otherwise, value should be a string.
setenvworks by modifying
process-environment; binding that variable with
letis also reasonable practice.
setenvreturns the new value of variable, or
nilif it removed variable from the environment.
This variable is a list of strings, each describing one environment variable. The functions
setenvwork by means of this variable.process-environment ⇒ ("l=/usr/stanford/lib/gnuemacs/lisp" "PATH=.:/user/lewis/bin:/usr/class:/nfsusr/local/bin" "USER=lewis" "TERM=ibmapa16" "SHELL=/bin/csh" "HOME=/user/lewis")
process-environmentcontains “duplicate” elements that specify the same environment variable, the first of these elements specifies the variable, and the other “duplicates” are ignored.
This variable holds the list of environment variables Emacs inherited from its parent process. It is computed during startup, see Startup Summary.
This variable holds a string which says which character separates directories in a search path (as found in an environment variable). Its value is
":"for Unix and GNU systems, and
";"for MS-DOS and MS-Windows.
This function takes a search path string such as would be the value of the
PATHenvironment variable, and splits it at the separators, returning a list of directory names.
nilin this list stands for “use the current directory.” Although the function's name says “colon,” it actually uses the value of
path-separator.(parse-colon-path ":/foo:/bar") ⇒ (nil "/foo/" "/bar/")
This variable holds the program name under which Emacs was invoked. The value is a string, and does not include a directory name.
This variable holds the directory from which the Emacs executable was invoked, or perhaps
nilif that directory cannot be determined.
nil, this is a directory within which to look for the lib-src and etc subdirectories. This is non-
nilwhen Emacs can't find those directories in their standard installed locations, but can find them in a directory related somehow to the one containing the Emacs executable.
This function returns the current 1-minute, 5-minute, and 15-minute load averages, in a list.
By default, the values are integers that are 100 times the system load averages, which indicate the average number of processes trying to run. If use-float is non-
nil, then they are returned as floating point numbers and without multiplying by 100.
If it is impossible to obtain the load average, this function signals an error. On some platforms, access to load averages requires installing Emacs as setuid or setgid so that it can read kernel information, and that usually isn't advisable.
If the 1-minute load average is available, but the 5- or 15-minute averages are not, this function returns a shortened list containing the available averages.(load-average) ⇒ (169 48 36) (load-average t) ⇒ (1.69 0.48 0.36) lewis@rocky % uptime 11:55am up 1 day, 19:37, 3 users, load average: 1.69, 0.48, 0.36
This variable holds the erase character that was selected in the system's terminal driver, before Emacs was started. The value is
nilif Emacs is running under a window system.