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128 lines
2.6 KiB
Groff
128 lines
2.6 KiB
Groff
.TH PLUMBER 4
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.SH NAME
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plumber \- file system for interprocess messaging
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.SH SYNOPSIS
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.B plumber
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[
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.B -f
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]
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[
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.B -p
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.I plumbing
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]
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.SH DESCRIPTION
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The
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.I plumber
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is a user-level file server that receives, examines, rewrites, and dispatches
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.MR plumb (7)
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messages between programs.
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Its behavior is programmed by a
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.I plumbing
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file (default
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.BR $HOME/lib/plumbing )
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in the format of
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.MR plumb (7) .
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.PP
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Its services are posted via
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.MR 9pserve (4)
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as
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.BR plumb ,
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and consist of two
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pre-defined files,
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.B plumb/send
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and
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.BR plumb/rules ,
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and a set of output
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.I ports
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for dispatching messages to applications.
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.PP
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Programs use
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.B fswrite
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(see
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.MR 9pclient (3) )
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to deliver messages to the
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.B send
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file, and
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.I fsread
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to receive them from the corresponding port.
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For example,
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.MR sam (1) 's
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.B plumb
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menu item or the
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.B B
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command cause a message to be sent to
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.BR plumb/send ;
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.B sam
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in turn reads from, by convention,
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.B plumb/edit
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to receive messages about files to open.
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.PP
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A copy of each message is sent to each client that has the corresponding port open.
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If none has it open, and the rule has a
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.B plumb
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.B client
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or
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.B plumb
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.B start
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rule, that rule is applied.
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A
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.B plumb
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.B client
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rule causes the specified command to be run
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and the message to be held for delivery when the port is opened.
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A
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.B plumb
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.B start
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rule runs the command but discards the message.
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If neither
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.B start
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or
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.B client
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is specified and the port is not open,
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the message is discarded and a write error is returned to the sender.
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.PP
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The set of output ports is determined dynamically by the
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specification in the plumbing rules file: a port is created for each unique
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destination of a
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.B plumb
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.B to
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rule.
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.PP
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The set of rules currently active may be examined by reading the file
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.BR plumb/rules ;
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appending to this file adds new rules to the set, while
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creating it (opening it with
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.BR OTRUNC )
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clears the rule set.
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Thus the rule set may be edited dynamically with a traditional text editor.
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However, ports are never deleted dynamically; if a new set of rules does not
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include a port that was defined in earlier rules, that port will still exist (although
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no new messages will be delivered there).
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.PP
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The
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.B -f
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option causes the process to run in the foreground.
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.SH FILES
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.TF $HOME/lib/plumbing
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.TP
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.B $HOME/lib/plumbing
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default rules file
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.TP
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.B \*9/plumb
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directory to search for files in
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.B include
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statements
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.TP
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.B plumb
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mount name for
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.MR plumber (4) .
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.SH SOURCE
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.B \*9/src/cmd/plumb
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.SH "SEE ALSO"
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.MR plumb (1) ,
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.MR plumb (3) ,
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.MR plumb (7)
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.\" .SH BUGS
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.\" .IR Plumber 's
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.\" file name space is fixed, so it is difficult to plumb
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.\" messages that involve files in newly mounted services.
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