Provided by: runit_2.1.2-44ubuntu2_amd64 
NAME
svlogd - runit's service logging daemon
SYNOPSIS
svlogd [-tttv] [-r c] [-R xyz] [-l len] [-b buflen] logs
DESCRIPTION
logs consists of one or more arguments, each specifying a directory.
svlogd continuously reads log data from its standard input, optionally filters log messages, and writes
the data to one or more automatically rotated logs.
Recent log files can automatically be processed by an arbitrary processor program when they are rotated,
and svlogd can be told to alert selected log messages to standard error, and through udp.
svlogd runs until it sees end-of-file on standard input or is sent a TERM signal, see below.
LOG DIRECTORY
A log directory log contains some number of old log files, and the current log file current. Old log
files have a file name starting with @ followed by a precise timestamp (see the daemontools' tai64n
program), indicating when current was rotated and renamed to this file.
A log directory additionally contains the lock file lock, maybe state and newstate, and optionally the
file config. svlogd creates necessary files if they don't exist.
If svlogd has trouble opening a log directory, it prints a warning, and ignores this log directory. If
svlogd is unable to open all log directories given at the command line, it exits with an error. This can
happen on start-up or after receiving a HUP signal.
LOG FILE ROTATION
svlogd appends selected log messages to the current log file. If current has size bytes or more (or
there is a new-line within the last len of size bytes), or is older than a specified amount of time,
current is rotated:
svlogd closes current, changes permission of current to 0755, renames current to @timestamp.s, and starts
with a new empty current. If svlogd sees num or more old log files in the log directory, it removes the
oldest one. Note that this doesn't decrease the number of log files if there are already more than num
log files, this must be done manually, e.g. for keeping 10 log files:
ls -1 \@* |sort |sed -ne '10,$p' |xargs rm
PROCESSOR
If svlogd is told to process recent log files, it saves current to @timestamp.u, feeds @timestamp.u
through ``sh -c "processor"'' and writes the output to @timestamp.t. If the processor finishes
successfully, @timestamp.t is renamed to @timestamp.s, and @timestamp.u is deleted; otherwise
@timestamp.t is deleted and the processor is started again. svlogd also saves any output that the
processor writes to file descriptor 5, and makes that output available on file descriptor 4 when running
processor on the next log file rotation.
A processor is run in the background. If svlogd sees a previously started processor still running when
trying to start a new one for the same log, it blocks until the currently running processor has finished
successfully. Only the HUP signal works in that situation. Note that this may block any program feeding
its log data to svlogd.
CONFIG
On startup, and after receiving a HUP signal, svlogd checks for each log directory log if the
configuration file log/config exists, and if so, reads the file line by line and adjusts configuration
for log as follows:
If the line is empty, or starts with a ``#'', it is ignored. A line of the form
ssize sets the maximum file size of current when svlogd should rotate the current log file to size
bytes. Default is 1000000. If size is zero, svlogd doesn't rotate log files. You should set
size to at least (2 * len).
nnum sets the number of old log files svlogd should maintain to num. If svlogd sees more that num old
log files in log after log file rotation, it deletes the oldest one. Default is 10. If num is
zero, svlogd doesn't remove old log files.
Nmin sets the minimum number of old log files svlogd should maintain to min. min must be less than
num. If min is set, and svlogd cannot write to current because the filesystem is full, and it
sees more than min old log files, it deletes the oldest one.
ttimeout
sets the maximum age of the current log file when svlogd should rotate the current log file to
timeout seconds. If current is timeout seconds old, and is not empty, svlogd forces log file
rotation.
!processor
tells svlogd to feed each recent log file through processor (see above) on log file rotation. By
default log files are not processed.
ua.b.c.d[:port]
tells svlogd to transmit the first len characters of selected log messages to the IP address
a.b.c.d, port number port. If port isn't set, the default port for syslog is used (514). len can
be set through the -l option, see below. If svlogd has trouble sending udp packets, it writes
error messages to the log directory. Attention: logging through udp is unreliable, and should be
used in private networks only.
Ua.b.c.d[:port]
is the same as the u line above, but the log messages are no longer written to the log directory,
but transmitted through udp only. Error messages from svlogd concerning sending udp packages
still go to the log directory.
pprefix
tells svlogd to prefix each line to be written to the log directory, to standard error, or through
UDP, with prefix.
If a line starts with a -, +, e, or E, svlogd matches the first len characters of each log message
against pattern and acts accordingly:
-pattern
the log message is deselected.
+pattern
the log message is selected.
epattern
the log message is selected to be printed to standard error.
Epattern
the log message is deselected to be printed to standard error.
Initially each line is selected to be written to log/current. Deselected log messages are discarded from
log. Initially each line is deselected to be written to standard err. Log messages selected for
standard error are written to standard error.
PATTERN MATCHING
svlogd matches a log message against the string pattern as follows:
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 pattern in the
log message one or more times. A star before the end of pattern matches any string in the log message
that does not include the next character in pattern. A star at the end of pattern matches any string.
Timestamps optionally added by svlogd are not considered part of the log message.
An svlogd pattern is not a regular expression. For example consider a log message like this
2005-12-18_09:13:50.97618 tcpsvd: info: pid 1977 from 10.4.1.14
The following pattern doesn't match
-*pid*
because the first star matches up to the first p in tcpsvd, and then the match fails because i is not s.
To match this log message, you can use a pattern like this instead
-*: *: pid *
OPTIONS
-t timestamp. Prefix each selected line with a precise timestamp (see the daemontools' tai64n
program) when writing to log or to standard error.
-tt timestamp. Prefix each selected line with a human readable, sortable UTC timestamp of the form
YYYY-MM-DD_HH:MM:SS.xxxxx when writing to log or to standard error.
-ttt timestamp. Prefix each selected line with a human readable, sortable UTC timestamp of the form
YYYY-MM-DDTHH:MM:SS.xxxxx when writing to log or to standard error.
-r c replace. c must be a single character. Replace non-printable characters in log messages with c.
Characters are replaced before pattern matching is applied.
-R xyz replace charset. Additionally to non-printable characters, replace all characters found in xyz
with c (default ``_'').
-l len line length. Pattern matching applies to the first len characters of a log message only. Default
is 1000.
-b buflen
buffer size. Set the size of the buffer svlogd uses when reading from standard input and writing
to logs to buflen. Default is 1024. buflen must be greater than len. For svlogd instances that
process a lot of data in short time, the buffer size should be increased to improve performance.
-v verbose. Print verbose messages to standard error.
SIGNALS
If svlogd is sent a HUP signal, it closes and reopens all logs, and updates their configuration according
to log/config. If svlogd has trouble opening a log directory, it prints a warning, and discards this log
directory. If svlogd is unable to open all log directories given at the command line, it exits with an
error.
If 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 processor subprocesses to finish if any, and exits
0 as soon as possible.
If svlogd is sent an ALRM signal, it forces log file rotation for all logs with a non empty current log
file.
SEE ALSO
sv(8), runsv(8), chpst(8), runit(8), runit-init(8), runsvdir(8), runsvchdir(8)
http://smarden.org/runit/
AUTHOR
Gerrit Pape <pape@smarden.org>
svlogd(8)