Environment variables in the host system affect the behavior of programs
supplied by groff
as follows. Normally, the path separator in
environment variables ending with ‘PATH’ is the colon; this may
vary depending on the operating system. For example, Windows uses a
semicolon instead.
GROFF_BIN_PATH
¶Locate groff
commands in these directories, followed by those in
PATH
. If not set, the installation directory of GNU roff
executables, documented in groff(1), is searched before
PATH
.
GROFF_COMMAND_PREFIX
¶Apply a prefix to certain GNU roff
commands.
groff
can be configured at compile time to apply a prefix to
the names of programs it provides that had counterparts in
AT&T troff
, so that name collisions are avoided at run
time. The default prefix is empty.
When used, this prefix is conventionally the letter ‘g’.
For example, GNU troff
would be installed as gtroff
.
Besides troff
, the prefix applies to the formatter wrapper
nroff
; the preprocessors eqn
, grn
,
pic
, refer
, tbl
, and soelim
; and
the utilities indxbib
and lookbib
.
GROFF_ENCODING
¶Specify the assumed character encoding of the input. groff
passes its value as an argument to the preconv
preprocessor’s
-e option. This variable’s existence implies the
groff
option -k. If set but empty, groff
runs preconv
without an -e option. groff
’s
-K option overrides GROFF_ENCODING
. See
preconv(7).
GROFF_FONT_PATH
¶Seek the selected output device’s directory of device and font description files in this list of directories. See Font Directories, gtroff(1), and groff_font(5).
GROFF_TMAC_PATH
¶Seek macro packages in this list of directories. See Macro Directories, gtroff(1), and groff_tmac(5).
GROFF_TMPDIR
¶Create temporary files in this directory. If not set, but TMPDIR
is, the latter is used instead. On Windows systems, if neither of the
foregoing are set, the environment variables TMP
and TEMP
(in that order) are checked also. Otherwise, temporary files are
created in a system-dependent default directory (on Unix and GNU/Linux
systems, usually /tmp). The grefer
, grohtml
,
and grops
commands use temporary files.
GROFF_TYPESETTER
¶Set the default output device. The -T dev option overrides it. If empty or unset, a default configured at build time, and documented in groff(1), is used.
SOURCE_DATE_EPOCH
¶Declare a time stamp (expressed as seconds since the Unix epoch) to use as the output creation time stamp in place of the current time. The time is converted to human-readable form using gmtime(3) and asctime(3) when the formatter starts up and stored in registers usable by documents and macro packages (see Built-in Registers).
TZ
¶Declare the time zone to use when converting the current time to
human-readable form; see tzset(3). If
SOURCE_DATE_EPOCH
is used, it is always converted to
human-readable form using UTC.