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)
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.
- !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
- log
messages matching pattern are printed to standard error.
- Epattern
- log messages
not matching pattern are printed to standard error.
Initially each line
is selected. Deselected log messages are discarded from log.
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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