groff: I/O
5.33 I/O
========
'gtroff' has several requests for including files:
-- Request: .so file
-- Request: .soquiet file
Replace the 'so' request's control line with the contents of the
file named by the argument, "sourcing" it. FILE is sought in the
directories specified by '-I' command-line option. If FILE does
not exist, a warning in category 'file' is produced and the request
has no further effect. ⇒Warnings, for information about the
enablement and suppression of warnings.
'so' can be useful for large documents; e.g., allowing each chapter
of a book to be kept in a separate file. However, files
interpolated with 'so' are not preprocessed; to overcome this
limitation, see the 'gsoelim(1)' man page.
Since GNU 'troff' replaces the entire control line with the
contents of a file, it matters whether 'file' is terminated with a
newline or not. Assume that file 'xxx' contains only the word
'foo' without a trailing newline.
$ printf 'foo' > xxx
The situation is
.so xxx
bar.
=> The situation is foobar.
'soquiet' works the same way, except that no warning diagnostic is
issued if FILE does not exist.
-- Request: .pso command
Read the standard output from the specified COMMAND and include it
in place of the 'pso' request.
It is an error to use this request in safer mode, which is the
default. Invoke GNU 'troff' or a front end with the '-U' option to
enable unsafe mode.
The comment regarding a final newline for the 'so' request is valid
for 'pso' also.
-- Request: .mso file
-- Request: .msoquiet file
Identical to the 'so' and 'soquiet' requests, respectively, except
that 'gtroff' searches for the specified FILE in the same
directories as macro files for the '-m' command-line option. If
the file name to be included has the form 'NAME.tmac' and it isn't
found, these requests try to include 'tmac.NAME' and vice versa.
-- Request: .trf file
-- Request: .cf file
Transparently output the contents of FILE. Each line is output as
if it were preceded by '\!'; however, the lines are _not_ subject
to copy mode interpretation. If the file does not end with a
newline, 'trf' adds one. Both requests cause a break.
When used in a diversion, these requests embed a node (⇒Gtroff
Internals) in it that, when reread, causes the contents of FILE
to be transparently copied to the output. In AT&T 'troff', the
contents of FILE are immediately copied to the output regardless of
whether there is a current diversion; this behaviour is so
anomalous that it must be considered a bug.
While 'cf' copies the contents of FILE completely unprocessed,
'trf' disallows characters such as NUL that are not valid 'gtroff'
input characters (⇒Identifiers).
For 'cf', within a diversion, "completely unprocessed" means that
each line of a file to be inserted is handled as if it were
preceded by '\!\\!'.
To define a macro 'x' containing the contents of file 'f', use
.ev 1
.di x
.trf f
.di
.ev
The calls to 'ev' prevent the partially collected output line from
becoming part of the diversion (⇒Diversions).
-- Request: .nx [file]
Force 'gtroff' to continue processing of the file specified as an
argument. If no argument is given, immediately jump to the end of
file.
-- Request: .rd [prompt [arg1 arg2 ...]]
Read from standard input, and include what is read as though it
were part of the input file. Text is read until a blank line is
encountered.
If standard input is a TTY input device (keyboard), write PROMPT to
standard error, followed by a colon (or send BEL for a beep if no
argument is given).
Arguments after PROMPT are available for the input. For example,
the line
.rd data foo bar
with the input 'This is \$2.' prints
This is bar.
Using the 'nx' and 'rd' requests, it is easy to set up form letters.
The form letter template is constructed like this, putting the following
lines into a file called 'repeat.let':
.ce
\*(td
.sp 2
.nf
.rd
.sp
.rd
.fi
Body of letter.
.bp
.nx repeat.let
When this is run, a file containing the following lines should be
redirected in. Requests included in this file are executed as though
they were part of the form letter. The last block of input is the 'ex'
request, which tells GNU 'troff' to stop processing. If this were not
there, 'troff' would not know when to stop.
Trent A. Fisher
708 NW 19th Av., #202
Portland, OR 97209
Dear Trent,
Len Adollar
4315 Sierra Vista
San Diego, CA 92103
Dear Mr. Adollar,
.ex
-- Request: .pi pipe
Pipe the output of 'gtroff' to the shell command(s) specified by
PIPE. This request must occur before 'gtroff' has a chance to
print anything.
It is an error to use this request in safer mode, which is the
default. Invoke GNU 'troff' or a front end with the '-U' option to
enable unsafe mode.
Multiple calls to 'pi' are allowed, acting as a chain. For
example,
.pi foo
.pi bar
...
is the same as '.pi foo | bar'.
The intermediate output format of GNU 'troff' is piped to the
specified commands. Consequently, calling 'groff' without the '-Z'
option normally causes a fatal error.
-- Request: .sy cmds
-- Register: \n[systat]
Execute the shell command(s) specified by CMDS. The output is not
saved anywhere, so it is up to the user to do so.
It is an error to use this request in safer mode; this is the
default. Give GNU 'troff' or a front end program the '-U' option
to enable unsafe mode.
The following code fragment introduces the current time into a
document.
.sy perl -e 'printf ".nr H %d\\n.nr M %d\\n.nr S %d\\n",\
(localtime(time))[2,1,0]' > /tmp/x\n[$$]
.so /tmp/x\n[$$]
.sy rm /tmp/x\n[$$]
\nH:\nM:\nS
This works by having the Perl script (run by 'sy') write 'nr'
requests that set the registers 'H', 'M', and 'S' to a temporary
file. The 'roff' document then reads the temporary file using the
'so' request.
The registers 'seconds', 'minutes', and 'hours', initialized at
startup of GNU 'troff', should satisfy most requirements. Use the
'af' request to format their values for output.
.af hours 00
.af minutes 00
.af seconds 00
\n[hours]:\n[minutes]:\n[seconds]
=> 02:17:54
The writable register 'systat' contains the return value of the
'system()' function executed by the last 'sy' request.
-- Request: .open stream file
-- Request: .opena stream file
Open the specified FILE for writing and associates the specified
STREAM with it.
The 'opena' request is like 'open', but if the file exists, append
to it instead of truncating it.
It is an error to use these requests in safer mode; this is the
default. Give GNU 'troff' or a front end program the '-U' option
to enable unsafe mode.
-- Request: .write stream data
-- Request: .writec stream data
Write to the file associated with the specified STREAM. The stream
must previously have been the subject of an open request. The
remainder of the line is interpreted as the 'ds' request reads its
second argument: an initial neutral double quote in CONTENTS is
stripped to allow embedding of leading spaces, and it is read in
copy mode.
The 'writec' request is like 'write', but only 'write' appends a
newline to the data.
-- Request: .writem stream xx
Write the contents of the macro or string XX to the file associated
with the specified STREAM.
XX is read in copy mode, i.e., already formatted elements are
ignored. Consequently, diversions must be unformatted with the
'asciify' request before calling 'writem'. Usually, this means a
loss of information.
-- Request: .close stream
Close the specified STREAM; the stream is no longer an acceptable
argument to the 'write' request.
Here a simple macro to write an index entry.
.open idx test.idx
.
.de IX
. write idx \\n[%] \\$*
..
.
.IX test entry
.
.close idx
-- Escape sequence: \Ve
-- Escape sequence: \V(ev
-- Escape sequence: \V[env]
Interpolate the contents of the specified environment variable ENV
(one-character name E, two-character name EV) as returned by the
function 'getenv(3)'. '\V' is interpreted even in copy mode (⇒
Copy Mode).
Info Catalog
groff: Suppressing Output
groff: GNU troff Reference
groff: Postprocessor Access