phpman > man > multilog(8)

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



NAME
       multilog  -  reads a sequence of lines from stdin and appends selected lines to any number of
       logs.

SYNOPSIS
       multilog script

DESCRIPTION
       script consists of any number of arguments. Each argument specifies one action.  The  actions
       are  carried  out  in  order  for  each  line  of  input. Note that actions may contain shell
       metacharacters that need to be quoted when multilog is run from a shell.

       multilog exits 0 when it sees the end of stdin. If stdin has a partial final line then multi‐‐
       log inserts a final newline.

       multilog  writes a message to stderr and exits 111, without reading any input, if it runs out
       of memory or if another multilog process is writing to one of the same automatically  rotated
       logs.

       If multilog has trouble writing to disk after it starts reading input, it writes a message to
       stderr, pauses, and tries again, without losing any data. Note that this may block  any  pro‐
       gram feeding input to multilog.

       If multilog receives a TERM signal, it will read and process data until the next newline, and
       then exit, leaving stdin at the first byte of data it has not processed.

SELECTING LINES
       Each line is initially selected. The action

       -pattern
              deselects the line if pattern matches the line. The action

       +pattern
              selects the line if pattern matches the line.

       pattern is a string of stars and non-stars. It matches any concatenation of  strings  matched
       by  all  the  stars and non-stars in the same order. A non-star matches itself. A star before
       the end of pattern matches any string that does not include the next character in pattern.  A
       star at the end of pattern matches any string.

       For example, the action

         +hello

       selects hello. It does not select hello world.

       The action

         -named[*]: Cleaned cache *

       deselects  named[135]: Cleaned cache of 3121 RRs. The first star matches any string that does
       not include a right bracket.

       The action

         -*

       deselects every line.

       To save memory, multilog actually checks pattern against only the first  1000  characters  of
       each line.

ALERTS
       The action

       e      prints (the first 200 bytes of) each selected line to stderr.

STATUS FILES
       The action

       =file  replaces  the  contents  of  file  with  (the first 1000 bytes of) each selected line,
              padded with newlines to 1001 bytes. There is no protection of file against power  out‐
              ages.

              For example, the sequence of actions

                   -*
                   +STAT*
                   =log/status

              maintains log/status as a copy of the most recent line starting with STAT.

TIMESTAMPING
       The action

       t      inserts  an  @, a precise timestamp, and a space in front of each line, using the same
              format as tai64n(8).  This is required to be the first action.

       Patterns apply to the line after the timestamp is inserted. For example, if

         multilog t '-*' '+* fatal: *' ./main

       reads the line

         fatal: out of memory

       then it will log a line such as

         @400000003b4a39c23294b13c fatal: out of memory

       with the first * matching the timestamp.

       You can use tai64nlocal(8) to convert these timestamps to human-readable form.

AUTOMATICALLY ROTATED LOGS
       If dir starts with a dot or slash then the action

       dir    appends each selected line to a log named dir.  If dir does not exist,  multilog  cre‐
              ates it.

              Do  not  attempt  to write to one log from two simultaneous multilog processes, or two
              actions in one process.

              The log format is as follows.  dir is a directory containing some number  of  old  log
              files, a log file named current, and other files for multilog to keep track of its ac‐
              tions. Each old log file has a name beginning with @, continuing with a precise  time‐
              stamp showing when the file was finished, and ending with one of the following codes:

       .s     This file is completely processed and safely written to disk.

       .u     This file was being created at the moment of an outage. It may have been truncated and
              has not been processed.

              Beware that NFS, async filesystems, and softupdates filesystems may discard files that
              were not safely written to disk before an outage.

              While multilog is running, current has mode 644. If multilog sees the end of stdin, it
              writes current safely to disk, and sets the mode of current to 744. When it  restarts,
              it sets the mode of current back to 644 and continues writing new lines.

              When  multilog  decides  that current is big enough, it writes current safely to disk,
              sets the mode of current to 744, and renames current as an old log file. The action

       ssize  sets the maximum file size for subsequent dir actions.  multilog will decide that cur‐
              rent is big enough if current has size bytes.  (multilog will also decide that current
              is big enough if it sees a newline within 2000 bytes of  the  maximum  file  size;  it
              tries  to  finish  log  files  at  line  boundaries.)   size  must be between 4096 and
              16777215. The default maximum file size is 99999.

              In versions 0.75 and above: If multilog receives an ALRM signal,  it  immediately  de‐
              cides that current is big enough, if current is nonempty.  The action

       nnum   sets  the  number  of log files for subsequent dir actions. After renaming current, if
              multilog sees num or more old log files, it removes the old log file with the smallest
              timestamp.  num must be at least 2. The default number of log files is 10. The action

       !processor
              sets  a processor for subsequent dir actions.  multilog will feed current through pro‐
              cessor and save the output as an old log file instead of current.  multilog will  also
              save  any  output that processor writes to descriptor 5, and make that output readable
              on descriptor 4 when it runs processor on the next log file. For reliability,  proces‐
              sor  must  exit  nonzero if it has any trouble creating its output; multilog will then
              run it again. Note that running processor may block any program feeding input to  mul‐‐
              tilog.

SEE ALSO
       supervise(8),   svc(8),   svok(8),  svstat(8),  svscanboot(8),  svscan(8),  readproctitle(8),
       fghack(8), pgrphack(8), tai64n(8),  tai64nlocal(8),  setuidgid(8),  envuidgid(8),  envdir(8),
       softlimit(8), setlock(8)

       http://cr.yp.to/daemontools.html



                                                                                         multilog(8)