.\" ENVIRONMENTS:  LC, TOS
.TH "environmental variable" "" "" Overview
.PC
.PP
An
.I "environmental variable"
is a variable that is set through the operating system, and which a
program can read at run time.
These variables are most commonly used to change the way a program behaves.
.PP
\*(PN uses the following environmental variables in its operation:
.if \nX=1 \{\
.DS
.ta 0.4i 2.0i
	\fBCCHEAD\fR	Variables at head of compilation command
	\fBCCTAIL\fR	Variables at tail of compilation command
	\fBINCDIR\fR	Directory that holds include files
	\fBLIBPATH\fR	Directories that hold libraries
	\fBPATH\fR	Directories that hold executable files
	\fBTIMEZONE\fR	Time zone information
	\fBTMPDIR\fR	Directory that holds temporary files
.DE
.PP
Because of the limited environment space available under many version of
MS-DOS, the variables
.BR INCDIR ,
.BR LIBPATH ,
and
.B TMPDIR
often are not set.
Instead, their information is placed into the file
.BR ccargs ,
which is built automatically when you install \*(PN.
You need to set the variable
.B TIMEZONE
only if you are writing programs that need exact time zone information. \}
.if \nX=2 \{\
.DS
.ta 0.4i 2.0i
	\fBINCDIR\fR	Directory that holds include files
	\fBLIBPATH\fR	Directories that hold libraries
	\fBPATH\fR	Directories that hold executable files
	\fBTIMEZONE\fR	Time zone information
	\fBTMPDIR\fR	Directory that holds temporary files
.DE
.PP
See the entry on
.B msh
for more information about how to set environmental variables. \}
.SH "See Also"
.B
.if \nX=1 Environment
.if \nX=2 Environment, msh
.R
