code: 9ferno

ref: e81c54ba2ecc673a4d5f8aed0e9b52841fe07b0d
dir: /man/4/logfile/

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.TH LOGFILE 4
.SH NAME
logfile \- memory-based append-only circular storage buffer
.SH SYNOPSIS
.B logfile
.RB [ \-\fIsize\fP ]
.I \fIfile\fP
.SH DESCRIPTION
.I Logfile
creates a name at
.I file
(the containing directory must already exist).
Each write to
.I file
appends the written data up to a maximum of
.I size
bytes; subsequent writes erase the existing
data in a circular fashion. A read from
.I file
will return any currently stored data, if any;
if there is none, then it will block until more
data becomes available.
Multiple readers will receive the data independently
of one another. If a writing process is consistently
producing data faster than a reading process, then
the data read will have some bytes elided; a write
is never blocked.
.SH SOURCE
.B /appl/cmd/logfile.b
.SH SEE ALSO
.IR wm-logwindow (1),
.IR sys-file2chan (2)
.SH BUGS
Restrictions on
.IR sys-file2chan (2)
mean that the
.I logfile
process will not terminate automatically
when its file is removed or unmounted.
.PP
There is no indication to a reader of any
missing data.
.PP
It is not possible to do a non-blocking
read of the log file.