buffchan - buffered file-writing backend for InterNetNews
buffchan [ -b ] [ -c lines ] [ -C seconds ] [ -d directory ] [ -f
num_fields ] [ -m map ] [ -p pidfile ] [ -l lines ] [ -L seconds ] [ -r
] [ -s filename_format ] [ -u ]
Buffchan reads lines from standard input and copies certain fields in
each line into files named by other fields within the line. Buffchan
is intended to be called by innd(8) as an exploder feed.
-b Once buffchan opens a file it keeps it open. The input must
therefore never specify more files than the number of available
descriptors can keep open. If the ‘‘-b’’ flag is used, the pro-
gram will allocate a buffer and attach it to the file using set-
If the ‘‘-c’’ flag is used, buffchan will close, and re-open, a
file after every lines lines are written to a file.
Similarly, the ‘‘-C’’ flag may be used to specify that all files
should be closed and re-opened every seconds seconds.
The ‘‘-d’’ flag may be used to specify a directory the program
should change to before starting. If this flag is used, then
the default for the ‘‘-s’’ flag is changed to be a simple
Buffchan input is interpreted as a sequence of lines. Each line
contains a fixed number of initial fields, followed by a vari-
able number of filename fields. All fields in a line are sepa-
rated by whitespace. The default number of initial fields is
one; the ‘‘-f’’ flag may be used to specify a different number
-m map Map files specify short names as aliases for domain names; see
filechan(8) for details and an example.
If the ‘‘-p’’ flag is used, the program will write a line con-
taining its process ID (in text) to the specified file.
If the ‘‘-l’’ flag is used, buffchan will call fflush(3) after
every lines lines are written to a file.
If the ‘‘-L’’ flag is used, all files will be flushed every n
-r By default, the program sends its error messages to
<pathlog in inn.conf>/errlog. To suppress this redirection and
send error messages to standard error, use the ‘‘-r’’ flag.
After the initial fields, each remaining field names a file to
write. The ‘‘-s’’ flag may be used to specify a format string
that maps the field to a file name. This is a sprintf(3) format
string which should have a single ‘‘%s’’ parameter which will be
given the contents of a non-initial field. The default value is
<pathoutgoing in inn.conf>/%s. See the description of this flag
-u If the ‘‘-u’’ flag is used, the program will request unbuffered
Buffchan can be invoked as an exploder feed (see newsfeeds(5)). As
such, if a line starts with an exclamation point it will be treated as
a command. There are three commands, described below:
flush The ‘‘flush’’ command closes and re-opens all open files;
‘‘flush xxx’’ which flushes only the specified site. These are
analogous to the ctlinnd(8) ‘‘flush’’ command, and can be
achieved by doing a ‘‘send "flush xxx"’’ command. Applications
can tell that the ‘‘flush’’ has completed by renaming the file
before issuing the command; buffchan has completed the command
when the original filename re-appears. If <$ac_cv_func_fchmod
in config.cache> is ‘‘yes’’, then buffchan also changes the
access permissions of the file from read-only for everyone to
read-write for owner and group as it flushes or closes each out-
put file. It will change the modes back to read-only if it re-
opens the same file.
drop The ‘‘drop’’ command is similar to the ‘‘flush’’ command except
that no files are re-opened. If given an argument, then the
specified site is dropped, otherwise all sites are dropped.
(Note that the site will be restarted if the input stream men-
tions the site.) When a ctlinnd ‘‘drop site’’ command is sent,
innd will automatically forward the command to buffchan for
sites listed as funnels feeding into this exploder. To drop all
sites, use the ctlinnd ‘‘send buffchan-site drop’’ command.
The map file (specified with the ‘‘-m’’ flag) is reloaded.
Written by Rich $alz <email@example.com> for InterNetNews. This is
revision 1.8, dated 2002/12/03.
ctlinnd(8), filechan(8), inn.conf(5), innd(8), newsfeeds(5).
Man(1) output converted with