jammy (8) svlogd.8.gz

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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)