groff: Built-in Registers
5.6.5 Built-in Registers
------------------------
The following lists some built-in registers that are not described
elsewhere in this manual. Any register that begins with a '.' is
read-only. A complete listing of all built-in registers can be found in
Register Index.
'\n[.F]'
This string-valued register returns the current input file name.
'\n[.H]'
Horizontal resolution in basic units.
'\n[.R]'
The number of number registers available. This is always 10000 in
GNU 'troff'; it exists for backward compatibility.
'\n[.U]'
If 'gtroff' is called with the '-U' command line option to activate
unsafe mode, the number register '.U' is set to 1, and to zero
otherwise. Groff Options.
'\n[.V]'
Vertical resolution in basic units.
'\n[seconds]'
The number of seconds after the minute, normally in the range 0
to 59, but can be up to 61 to allow for leap seconds. Initialized
at start-up of 'gtroff'.
'\n[minutes]'
The number of minutes after the hour, in the range 0 to 59.
Initialized at start-up of 'gtroff'.
'\n[hours]'
The number of hours past midnight, in the range 0 to 23.
Initialized at start-up of 'gtroff'.
'\n[dw]'
Day of the week (1-7).
'\n[dy]'
Day of the month (1-31).
'\n[mo]'
Current month (1-12).
'\n[year]'
The current year.
'\n[yr]'
The current year minus 1900. Unfortunately, the documentation of
UNIX Version 7's 'troff' had a year 2000 bug: It incorrectly
claimed that 'yr' contains the last two digits of the year. That
claim has never been true of either AT&T 'troff' or GNU 'troff'.
Old 'troff' input that looks like this:
'\" The following line stopped working after 1999
This document was formatted in 19\n(yr.
can be corrected as follows:
This document was formatted in \n[year].
or, to be portable to older 'troff' versions, as follows:
.nr y4 1900+\n(yr
This document was formatted in \n(y4.
'\n[.c]'
'\n[c.]'
The current _input_ line number. Register '.c' is read-only,
whereas 'c.' (a 'gtroff' extension) is writable also, affecting
both '.c' and 'c.'.
'\n[ln]'
The current _output_ line number after a call to the 'nm' request
to activate line numbering.
Miscellaneous, for more information about line numbering.
'\n[.x]'
The major version number. For example, if the version number is
1.03 then '.x' contains '1'.
'\n[.y]'
The minor version number. For example, if the version number is
1.03 then '.y' contains '03'.
'\n[.Y]'
The revision number of 'groff'.
'\n[$$]'
The process ID of 'gtroff'.
'\n[.g]'
Always 1. Macros should use this to determine whether they are
running under GNU 'troff'.
'\n[.A]'
If the command line option '-a' is used to produce an ASCII
approximation of the output, this is set to 1, zero otherwise.
Groff Options.
'\n[.O]'
This read-only register is set to the suppression nesting level
(see escapes '\O'). Suppressing output.
'\n[.P]'
This register is set to 1 (and to 0 otherwise) if the current page
is actually being printed, i.e., if the '-o' option is being used
to only print selected pages. Groff Options, for more
information.
'\n[.T]'
If 'gtroff' is called with the '-T' command line option, the number
register '.T' is set to 1, and zero otherwise. Groff
Options.
'\*[.T]'
A single read-write string register that contains the current
output device (for example, 'latin1' or 'ps'). This is the only
string register defined by 'gtroff'.
Info Catalog
groff: Assigning Formats
groff: Registers