buffchan - Buffered file-writing backend for INN
] [-c lines
] [ -d directory
] [-f num-fields
] [-L seconds
] [ -m map
] [-s format
reads lines from standard input and copies the initial fields in
each line to the files named by the remaining fields on the line.
is intended to be called by innd
as an exploder feed.
The input is interpreted as a sequence of lines. Each line contains a fixed
number of initial fields, followed by a variable number of filename fields.
All fields in a line are separated by whitespace and do not contain any
whitespace. The default number of initial fields is one.
For each line of input, buffchan
writes the initial fields, separated by
a space and followed by a newline, to each of the files named in the filename
fields. The output files are kept open and are only flushed or closed based on
the schedule given by the -c
, and -L
As an exploder feed (see newsfeeds
(5) for an explanation),
interprets lines beginning with an exclamation point as
commands. Besides "!begin" (which only marks the start of the feed),
there are three supported commands:
- !flush [site]
- The flush command closes and reopens all open files. An
optional site can be specified, in which case buffchan flushes only
that file. This command is analogous to the "ctlinnd flush"
command. This command can be sent via innd using "ctlinnd send
buffchan-site 'flush site'".
Applications can tell that flush has completed by renaming the file before
issuing the command. When the original file name has reappeared, the flush
is complete. If fchmod(3) is available, buffchan also
changes the file to read-only while it's actively writing to it and
changes it back to read/write once it has been closed. It will change the
mode back to read-only only if it reopens the same file.
- !drop [site]
- The drop command is similar to the flush command, except
that no files are reopened. If given an argument, only the specified site
is dropped; otherwise, all sites are dropped. (Note that a site will be
restarted if the input stream mentions the site again.)
When a "ctlinnd drop site" command is sent, innd will
automatically forward the command to buffchan if the site is listed
as a funnel feeding into the buffchan exploder. To drop all sites,
use "ctlinnd send buffchan-site drop".
- The map file specified with the -m option, if given,
will be reloaded.
opens a file, it keeps it open (in the absence of a drop
command). The input must therefore never specify more files than the maximum
number of files a process may open.
- Force the output to be buffered. (This is generally the
default, but it may depend on the operating system.) If -b is
given, a buffer size of BUFSIZ (a constant of the system standard I/O
library) is used.
- -c lines
- If the -c flag is given, buffchan will close
and reopen a file after every lines lines are written to the
- -C seconds
- If the -C flag is given, buffchan will close
and reopen a file if it has been open for more than seconds
- -d directory
- This flag may be used to specify a directory the program
should change to before starting. If this flag is used, the default for
the -s flag (see below) is changed to be a simple %s (in other
words, output files are considered to be relative to
- -f num-fields
- By default, each line is expected to contain one fixed
field followed by some number of filename fields. If this flag is given,
num-fields will be used as the number of initial fixed fields.
- -l lines
- If the -l flag is given, buffchan will flush
the output after every lines lines are written to a file.
- -L seconds
- If the -L flag is given, buffchan will flush
each output file every seconds seconds.
- -m map
- Map files translate the names in the filename fields on
each line into filenames that should be used instead. It's used primarily
when short names are used in newsfeeds, but the output files should
use the full domain names of remote peers.
In the map file, blank lines and lines starting with a number sign
("#") are ignored. All other lines should have two host names
separated by a colon. The first field is the name that may appear in the
input stream; the second field names the file to be used when the name in
the first field appears. For example:
# This is a comment
- -p pid-file
- If the -p option is given, buffchan will
write a line containing its process ID (in text) to the specified file
when it starts.
- By default, buffchan sends its error messages to
pathlog/errlog. To suppress this redirection and send error
messages to standard error, use the -r flag.
- The -s flag may be used to specify a format that
maps a filename from the filename fields at the end of each line to an
actual filename. This is a sprintf(3) format string that should
contain a single instance of %s, which will be replaced with the value of
the filename field (possibly after mapping with the map file from
-m). The default value is pathoutgoing/%s.
- If the -u flag is used, the output will be
is invoked with "-f 2" and given the following
news/software/b/132 <email@example.com> foo uunet
news/software/b/133 <firstname.lastname@example.org> uunet munnari
comp/sources/unix/2002 <email@example.com> foo uunet munnari
Then the file foo
will have these lines:
the file munnari
will have these lines:
and the file uunet
will have these lines:
Written by Rich $alz <firstname.lastname@example.org> for InterNetNews. Converted to
POD by Russ Allbery <email@example.com>.
$Id: buffchan.pod 9767 2014-12-07 21:13:43Z iulius $