G. Pape
runit
svlogd - runit’s service logging daemon
svlogd [-ttv] [-r c] [-R
xyz] [-l len] [-b buflen] logs
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.
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 tai64n(8)), 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.
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 dir, it removes the oldest one.
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.u is deleted and @timestamp.t
is renamed to @timestamp.s, 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.
On startup, and after receiving a HUP signal, svlogd checks
for each 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, less than two characters long, 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 maximum 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.
- 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.
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.
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.
- -t
- timestamp. Prefix
each selected line with a precise timestamp (see tai64n(8)) 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.
- -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.
- -v
- verbose. Print verbose messages to standard error.
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.
runsv(8), runsvctrl(8),
runsvstat(8), chpst(8), runit(8), runit-init(8), runsvdir(8), runsvchdir(8),
utmpset(8), multilog(8)
http://smarden.org/runit/
Gerrit Pape <pape@smarden.org>
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