X Window System environment variables

Table 1 provides a list of environment variables that can be set to affect the behavior of X Window System applications.

Table 1. Environment variables for the X Window System interface
Environment variable	Description
DISPLAY	Contains the name of the display to be used. There is no default value. See note 1.
ICEAUTHORITY	This variable identifies where the authentication information is located.
LANG	Determines the locale category for native language, local customs, and coded character set in the absence of the LC_ALL and other LC_* ( LC_COLLATE, LC_CTYPE, LC_MESSAGES, LC_MONETARY, LC_NUMERIC, LC_TIME) environment variables. See note 2.
LC_CTYPE	Determine the locale category for character handling functions, such as tolower(), toupper(), and isalpha(). This environment variable determines the interpretation of sequences of bytes of text data as characters (for example, single as opposed to multibyte characters), the classification of characters (for example, alpha, digit, graph), and the behavior of character classes.
SESSION_MANAGER	If defined, causes a Session Shell widget to connect to a session manager. There is no default value.
XAPPLRESDIR	Specifies the directory to search for files that contain application defaults.
XAUTHORITY	Specifies the name of the authority file on the local host.
XCMSDB	Specifies the name of a color name database file.
XENVIRONMENT	Contains the full path name of the file that contains resource defaults. There is no default value.
XFILESEARCHPATH	Used by XtResolvePathname as a default path. There is no default value.
XKEYSYMDB	Specifies the location of the XKEYSYMDB.
XLOCALEDIR	Specifies the directory to search for locale files. The default value is /usr/lib/X11/locale.
XMODIFIERS	Can be set to contain additional information important for the current locale setting. See note 3.
XUSERFILESEARCHPATH	Specifies where to find the personal X resources files used to configure an application.
XWTRACE	Controls the generation of socket-level communications traces between Xlib and the X Window System server. These traces are as follows: XWTRACE undefined or 0: No trace generated XWTRACE=1: Error messages XWTRACE>=2: API function tracing for TRANS functions There is no default value. The output is sent to stderr.
XWTRACELC	If defined, causes a trace of locale-sensitive routines. Possible values are: XWTRACELC undefined or 0: No trace generated XWTRACELC=1: Error messages XWTRACELC>=2: All available trace information There is no default value. The output is sent to stderr. See note 4.
Notes: In the following example, royal.csc.ibm.com is the name of the workstation running the X Window System server. The display is indicated by :0.0, and is specified this way in almost all cases. `export DISPLAY=royal.csc.ibm.com:0.0` This can be used by applications to determine the language to use for error messages, instructions, collating sequences, date formats, and so on. Typically set to @im=<input-method> to enable a particular input method. If XWTRACELC is defined, a routine flow trace is generated. If XWTRACELC=2, more detailed information is provided.