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svlogd(8)                   System Manager's Manual                  svlogd(8)

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 proces-
       sor program when they are rotated, and svlogd can be told to alert  se-
       lected 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 cur-
       rent  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 direc-
       tories  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  cur-
       rent 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  success-
       fully,  @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  pro-
              cessed.

       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 pack-
              ages still go to the log directory.

       pprefix
              tells svlogd to prefix each line to be written to the log direc-
              tory, 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.   Dese-
       lected log messages are discarded from log.  Initially each line is de-
       selected 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 be-
              fore pattern matching is applied.

       -R xyz replace charset.  Additionally to non-printable characters,  re-
              place all characters found in xyz with c (default ``_'').

       -l len line  length.  Pattern matching applies to the first len charac-
              ters of a log message only.  Default is 1000.

       -b buflen
              buffer size.  Set the size of the buffer svlogd uses when  read-
              ing  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 up-
       dates their configuration according to log/config.  If svlogd has trou-
       ble 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 buf-
       fer, 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 AT smarden.org>

                                                                     svlogd(8)