BUFFCHAN(8)BUFFCHAN(8)NAMEbuffchan - buffered file-writing backend for InterNetNews
SYNOPSISbuffchan [ -b ] [ -c lines ] [ -C seconds ] [ -d directory ] [ -f
fields ] [ -m map ] [ -p pidfile ] [ -l lines ] [ -L seconds ] [ -r ] [
-s file_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.
Buffchan input is interpreted as a set of lines. Each line contains a
fixed number of initial fields, followed by a variable number of file‐
name fields. All fields in a line are separated by whitespace. The
default number of initial fields is one; the ``-f'' flag may be used to
specify a different number of fields. See filechan(8) for an example.
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 field. The
default value is /var/spool/news/out.going/%s. See the description of
this flag in filechan(8). 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
Once buffchan opens a file it keeps it open. The input must therefore
never specify more files than can the number of available descriptors
can keep open. If the ``-b'' flag is used, the program will allocate a
buffer and attach it to the file using setbuf(3). If the ``-u'' flag
is used, the program will request unbuffered output.
If the ``-l'' flag is used with a number n, then buffchan will call
fflush(3) after every n lines are written to a file. If the ``-c''
flag is used with a number n, then buffchan will close, and re-open, a
file after every n lines are written to a file.
If the ``-L'' flag is used with a number n, then all files will be
flushed every n seconds. Similarly, the ``-C'' flag may be used to
specify that all files should be closed and re-opened every n seconds.
By default, the program sets its standard error to
/var/spool/news/data/errlog. To suppress this redirection, use the
If the ``-p'' flag is used, the program will write a line containing
its process ID (in text) to the specified file.
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.
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 output 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 any files are not re-opened. If given an argument, then the spec‐
ified site is dropped, otherwise all sites are dropped. (Note that the
site will be restarted if the input stream mentions the site.) When a
ctlinnd ``drop site'' command is sent, innd will automatically forward
the command to buffchan if the site is a funnel that feeds into this
exploder. To drop all sites, use the ctlinnd ``send buffchan-site
The map file (specified with the ``-m'' flag) is reloaded.
Written by Rich $alz <email@example.com> for InterNetNews. This is
revision 1.7, dated 1993/03/18.
SEE ALSOctlinnd(8), filechan(8), innd(8), newsfeeds(5).