When set to "on," this environment variable indicates that
POSIX-style terminal semantics are on.
Specifies the type of terminal.
Contains either the location of the termcap file, as an
absolute path name (it must start with /), or a termcap
terminal description entry, to be used instead of the termcap entry
for the current terminal type. If it contains an entry, the entry
has no newlines.
A space- or colon-separated list of absolute file names. If
TERMCAP is not set, clear(1) searches for the
appropriate terminal entry in these files.