# phpman > man > multilog(8) [multilog(8)](https://www.chedong.com/phpMan.php/man/multilog/8/markdown) System Manager's Manual [multilog(8)](https://www.chedong.com/phpMan.php/man/multilog/8/markdown) ## 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)](https://www.chedong.com/phpMan.php/man/tai64n/8/markdown). 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)](https://www.chedong.com/phpMan.php/man/tai64nlocal/8/markdown) 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 **s**_size_ 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 **n**_num_ 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)](https://www.chedong.com/phpMan.php/man/supervise/8/markdown), [svc(8)](https://www.chedong.com/phpMan.php/man/svc/8/markdown), [svok(8)](https://www.chedong.com/phpMan.php/man/svok/8/markdown), [svstat(8)](https://www.chedong.com/phpMan.php/man/svstat/8/markdown), [svscanboot(8)](https://www.chedong.com/phpMan.php/man/svscanboot/8/markdown), [svscan(8)](https://www.chedong.com/phpMan.php/man/svscan/8/markdown), [readproctitle(8)](https://www.chedong.com/phpMan.php/man/readproctitle/8/markdown), [fghack(8)](https://www.chedong.com/phpMan.php/man/fghack/8/markdown), [pgrphack(8)](https://www.chedong.com/phpMan.php/man/pgrphack/8/markdown), [tai64n(8)](https://www.chedong.com/phpMan.php/man/tai64n/8/markdown), [tai64nlocal(8)](https://www.chedong.com/phpMan.php/man/tai64nlocal/8/markdown), [setuidgid(8)](https://www.chedong.com/phpMan.php/man/setuidgid/8/markdown), [envuidgid(8)](https://www.chedong.com/phpMan.php/man/envuidgid/8/markdown), [envdir(8)](https://www.chedong.com/phpMan.php/man/envdir/8/markdown), [softlimit(8)](https://www.chedong.com/phpMan.php/man/softlimit/8/markdown), [setlock(8)](https://www.chedong.com/phpMan.php/man/setlock/8/markdown) [multilog(8)](https://www.chedong.com/phpMan.php/man/multilog/8/markdown)