utility should be scheduled to run periodically by
When it is executed it archives log files if necessary.
If a log file
is determined to require archiving,
rearranges the files so that
the last period's logs in it,
has the next to last
period's logs in it, and so on, up to a user-specified number of
Optionally the archived logs can be compressed to save
A log can be archived for three reasons:
It is larger than the configured size (in kilobytes).
A configured number of hours have elapsed since the log was last
This is the specific configured hour for rotation of the log.
The granularity of
is dependent on how often it is scheduled to run by
Since the program is quite fast, it may be scheduled to run every hour
without any ill effects,
and mode three (above) assumes that this is so.
The following options can be used with
for its configuration file.
into which archived log files will be written.
If a relative path is given,
it is appended to the path of each log file
and the resulting path is used as the directory
into which the archived log for that log file will be written.
If an absolute path is given,
all archived logs are written into the given
If any component of the path
does not exist,
it will be created when
which all log files will be relative to.
To allow archiving of logs outside the root, the
passed to the
option is unaffected.
in verbose mode.
In this mode it will print out each log and its
reasons for either trimming that log or skipping it.
not to trim the logs, but to print out what it would do if this option
were not specified.
Remove the restriction that
must be running as root.
will not be able to send a HUP signal to
so this option should only be used in debugging.
should not send any signals to any daemon processes that it would
normally signal when rotating a log file.
For any log file which is rotated, this option will usually also
mean the rotated log file will not be compressed if there is a
daemon which would have been signalled without this option.
However, this option is most likely to be useful when specified
option, and in that case the compression will be done.
If specified once, then
will create any log files which do not exist, and which have the
flag specified in their config file entry.
If specified multiple times, then
will create all log files which do not already exist.
If log files are given on the command-line, then the
will only apply to those specific log files.
to trim the logs, even if the trim conditions have not been met.
option is useful for diagnosing system problems by providing you with
fresh logs that contain only the problems.
Do not perform any rotations.
This option is intended to be used with the
options when creating log files is the only objective.
should rotate a given list of files, even if trim conditions are not
met for those files.
is only used in the messages written to the log files which are
This differs from the
option in that one or more log files must also be specified, so that
will only operate on those specific files.
This option is mainly intended for the daemons or programs which write
some log files, and want to trigger a rotate based on their own criteria.
With this option they can execute
to trigger the rotate when they want it to happen, and still give the
system administrator a way to specify the rules of rotation (such as how
many backup copies are kept, and what kind of compression is done).
When a daemon does execute
option, it should make sure all of the log files are closed before
and then it should re-open the files after
Usually the calling process will also want to specify the
will not send a signal to the very process which called it to force
Skipping the signal step will also mean that
will return faster, since
normally waits a few seconds after any signal that is sent.
If additional command line arguments are given,
will only examine log files that match those arguments; otherwise, it
will examine all files listed in the configuration file.
Previous versions of the
utility used the dot (``.'') character to
distinguish the group name.
Fx 3.3 ,
this has been changed to a colon (``:'') character so that user and group
names may contain the dot character.
The dot (``.'') character is still
accepted for backwards compatibility.
utility originated from
Nx and first appeared in
Fx 2.2 .
An Theodore Ts'o ,
MIT Project Athena
Copyright 1987, Massachusetts Institute of Technology