path: root/man/svlogd.8

.TH svlogd 8
.SH NAME
svlogd \- runit's service logging daemon
.SH SYNOPSIS
.B svlogd
[\-tv] [\-r
.I c\fR] [\-R
.I xyz\fR] [\-l
.I n\fR] [\-b
.I n\fR]
.I logs
.SH DESCRIPTION
.I logs
consists of one or more arguments, each specifying a directory.
.P
.B svlogd
continuously reads log data from its standard input, optionally filters log
messages, and writes the data to one or more automatically rotated
.IR logs .
.P
Recent log files can automatically be processed by an arbitrary processor
program when they are rotated, and
.B svlogd
can be told to alert selected log messages to standard error.
.P
.B svlogd
runs until it sees end-of-file on standard input or is sent a TERM signal,
see below.

.SS LOG DIRECTORY
A log directory
.I log
contains some number of old log files, and the current log file
.IR current .
Old log files have a file name starting with
.I @
followed by a precise timestamp (see
.BR tai64n (8)),
indicating when
.I current
was rotated and renamed to this file.
.P
A log directory additionally contains the lock file
.IR lock ,
maybe
.I state
and
.IR newstate ,
and optionally the file
.IR config .
.B svlogd
creates necessary files if they don't exist.
.SS LOG FILE ROTATION
.B svlogd
appends selected log messages to the
.I current
log file.
If
.I current
has
.I size
bytes or more size (or there is a new-line within the last
.I len
of
.I size
bytes)
.I current
is rotated:
.P
.B svlogd
closes
.IR current ,
changes permission of
.I current
to 0755, renames
.I current
to
.RI @ timestamp\fR.s,
and starts with a new empty
.IR current .
If
.B svlogd
sees
.I num
or more old log files in
.IR dir ,
it removes the oldest.
.SS PROCESSOR
If
.B svlogd
is told to process recent log files, it saves
.I current
to
.RI @ timestamp\fR.u,
feeds
.RI @ timestamp\fR.u
through ``sh \-c "\fIprocessor\fR"''
and writes the output to
.RI @ timestamp\fR.t.
If the
.I processor
finishes successfully,
.RI @ timestamp\fR.u
is deleted and
.RI @ timestamp\fR.t
is renamed to
.RI @ timestamp\fR.s,
otherwise
.RI @ timestamp\fR.t
is deleted and the
.I processor
is started again.
.B svlogd
also saves any output that the
.I processor
writes to file descriptor 5, and make that output available on
file descriptor 4 when it runs
.I processor
on the next log file rotation.
.P
A
.I processor
is run in the background.
If
.B svlogd
sees a previously started
.I processor
still running when trying to start a new one for the same
.IR log ,
it blocks until the currently running
.I processor
has finished successfully.
Only the HUP signal works in that situation.
Note that this may block any program feeding its log data to
.BR svlogd.

.SS CONFIG
On startup, and after receiving a HUP signal,
.B svlogd
checks for each
.I log
if the configuration file
.I log/config
exists, and if so, reads the file line by line and adjusts configuration for
.I log
as follows:
.P
If the line is empty, less than two characters long, or starts with a ``#'',
it is ignored.
A line of the form
.TP
.RI s size
sets the maximum file size of
.I current
when
.B svlogd
should rotate the current log file to
.I size
bytes.
Default is 1000000.
If
.I size
is zero,
.B svlogd
doesn't rotate log files.
You should set
.I size
to at least (2 *
.IR len ).
.TP
.RI n num
sets the maximum number of old log files
.B svlogd
should maintain to
.IR num .
If
.B svlogd
sees more that
.I num
old log files in
.I log
after log file rotation, it deletes the oldest one.
Default is 10.
.TP
.RI ! processor
tells
.B svlogd
to feed each recent log file through
.I processor
(see above) on log file rotation.
By default log files are not processed.
.P
If a line starts with a
.IR \- ,
.IR + ,
.IR e ,
or
.IR E ,
.B svlogd
matches the first
.I len
characters of each log message against
.I pattern
and acts accordingly:
.TP
.RI \- pattern
the log message is deselected.
.TP
.RI + pattern
the log message is selected
.TP
.RI e pattern
log messages matching
.I pattern
are printed to standard error.
.TP
.RI E pattern
log messages not matching
.I pattern
are printed to standard error.
.P
Initially each line is selected.
Deselected log messages are discarded from
.IR log .
.SH PATTERN MATCHING
.B svlogd
matches a log message against the string
.I pattern
as follows:
.P
.I pattern
is applied to the log message one character by one, starting with the first.
A character not a star (``*'') and not a plus (``+'') matches itself.
A plus matches the next character in
.I pattern
in the log message one or more times.
A star before the end of
.I pattern
matches any string in the log message that does not include the next
character in
.IR pattern .
A star at the end of
.I pattern
matches any string.
.SH OPTIONS
.TP
.B \-t
timestamp.
Prefix each selected line with a precise timestamp (see
.BR tai64n (8))
when writing to
.I log
or to standard error.
.TP
.B \-r \fIc
replace.
.I c
must be a single character.
Replace non-printable characters in log messages with
.IR c .
Characters are replaced before pattern matching is applied.
.TP
.B \-R \fIxyz
replace charset.
Additionally to non-printable characters, replace all characters found in
.I xyz
with
.I c
(default ``_'').
.TP
.B \-l \fIlen
line length.
Pattern matching applies to the first
.I len
characters of a log message only.
Default is 1000.
.TP
.B \-b \fIbuflen
buffer size.
Set the size of the buffer
.B svlogd
uses when reading from standard input and writing to
.I logs
to
.IR buflen .
Default is 1024.
.I buflen
must be greater than
.IR len .
.TP
.B \-v
verbose.
Print verbose messages to standard error.
.SH SIGNALS
If
.B svlogd
is sent a HUP signal, it closes and reopens all
.IR logs ,
and updates their configuration according to
.IR log/config .
.P
If
.B svlogd
is sent a TERM signal, or if it sees end-of-file on standard input, it stops
reading standard input, processes the data in the buffer, waits for all
.I processor
subprocesses to finish if any, and exits 0 as soon as possible.
.P
If
.B svlogd
is sent an ALRM signal, it forces log file rotation for all
.I logs
with a non empty
.I current
log file.
.SH SEE ALSO
runsv(8),
runsvstat(8),
runsvctrl(8),
runsvdir(8),
runsvchdir(8),
runit(8),
runit-init(8),
multilog(8)
.P
http://smarden.org/runit/
.SH AUTHOR
Gerrit Pape <pape@smarden.org>