NEWSYSLOG(8) BSD System Manager's Manual NEWSYSLOG(8)
newsyslog -- rotate log files
newsyslog [-Fmnrv] [-a directory] [-f config_file] [log ...]
The newsyslog utility rotates log files when they exceed a configurable
size or age. The log file is renamed to log.0 and an empty file is cre-
ated in its place. An archive of older logs may be kept: in order of
increasing age, these files are named log.1, log.2, and so on. When
their number exceeds a given limit, the oldest is removed. The archived
logs may also be compressed.
The options are as follows:
Specify a directory into which archived log files will be writ-
ten. If directory is a relative path, it is appended to the par-
ent directory of each log and the archived log is stored in the
result. If an absolute path is given, all archived logs are
stored in the given directory. If directory does not exist for a
specified log, it is ignored for that entry and the log is
rotated as if the -a option was not specified.
-F Force newsyslog to trim logs regardless of the size and/or age
requirements specified in /etc/newsyslog.conf. This option may
be combined with the -n or -v flags to aid in debugging problems
Use config_file instead of /etc/newsyslog.conf for the configura-
-m Monitoring mode; only entries marked with an 'M' in flags are
processed. For each log file being monitored, any log output
since the last time newsyslog was run with the -m flag is mailed
to the user listed in the monitor notification section.
-n Do not trim the logs, but instead print out what would be done if
this option were not specified.
-r Removes the restriction that newsyslog must be running as root.
Note that in this mode newsyslog will not be able to send a
SIGHUP signal to syslogd(8).
-v Place newsyslog in verbose mode. In this mode it will print out
each log and its reasons for either trimming that log or skipping
In the default system configuration, newsyslog is run by cron(8), but it
may also be run manually. If one or more log files are specified on the
command line, only the specified files are rotated. Note that each log
specified must have an entry in /etc/newsyslog.conf.
A log can be archived because of two reasons: The log file can have grown
bigger than a preset size in kilobytes, or a preset number of hours may
have elapsed since the last log archive. The granularity of newsyslog is
dependent on how often it is scheduled to run in cron(8). Since the pro-
gram is quite fast, it may be scheduled to run every hour without any ill
When starting up, newsyslog reads in a configuration file to determine
which logs should be looked at. By default, this configuration file is
/etc/newsyslog.conf. Each line of the file contains information about a
particular log file that should be handled by newsyslog. Each line has
five mandatory fields and up to three optional fields, with whitespace
separating each field. Blank lines or lines beginning with a hash mark
('#') are ignored. The fields of the configuration file are as follows:
logfile_name The full pathname of the system log file to be
owner:group This optional field specifies the owner and group for
the archive file. The ':' is essential, even if the
owner or group field is left blank. The fields may be
numeric, or a name which is looked up in the system
password and group databases. For backwards compati-
bility, a '.' may be used instead of a ':'. If either
owner or group is not specified, the owner and/or group
of the existing log file is used.
mode File mode (in octal) to use for created log files and
count The number of archives to be kept besides the log file
size When the size of the log file (in kilobytes) reaches
this point, the log file is trimmed as described above.
If this field is replaced by an '*', or set to '0',
then the size of the log file is not taken into account
when determining when to trim the log file. By
default, files smaller than 256 bytes are not rotated
unless the 'B' (binary) flag is set or the -F option is
specified. This prevents newsyslog from rotating files
consisting solely of a message indicating that the log
file has been turned over.
when The when field can consist of an interval, a specific
time, or both. If the when field consists of an aster-
isk ('*'), log rotation will depend only on the con-
tents of the size field. Otherwise, the when field
consists of an optional interval in hours, possibly
followed by an '@'-sign and a time in a restricted
format or by a '$'-sign and a time specification for
logfile rotation at a fixed time once per day, per week
or per month.
If a time is specified, the log file will only be
trimmed if newsyslog is run within one hour of the
specified time. If an interval is specified, the log
file will be trimmed if that many hours have passed
since the last rotation. When both a time and an
interval are specified, both conditions must be satis-
fied for the rotation to take place.
There is no provision for the specification of a time
zone. There is little point in specifying an explicit
minutes or seconds component in the current implementa-
tion, since the only comparison is 'within the hour'.
ISO 8601 restricted time format: The lead-in character
for a restricted time is an '@'-sign. The particular
format of the time in restricted is:
[[[[[cc]yy]mm]dd][T[HH[MM[SS]]]]]. Optional date
fields default to the appropriate component of the cur-
rent date; optional time fields default to midnight.
For example, if today is January 22, 1999, the follow-
ing date specifications are all equivalent:
Day, week and month time format: The lead-in character
for day, week and month specification is a dollar sign
($). The particular format of day, week and month
specification is: [DHH], [Ww[DHH]], and [Mdd[DHH]],
respectively. Optional time fields default to mid-
night. The ranges for day and hour specifications are:
HH hours, range 0 ... 23
w day of week, range 0 ... 6, 0 = Sunday
dd day of month, range 1 ... 31, or the let-
ter L or l to specify the last day of the
$D0 rotate every night at midnight (same as
$D23 rotate every day at 23:00 hr (same as
$W0D23 rotate every week on Sunday at 23:00 hr
$W5D16 rotate every week on Friday at 16:00 hr
$M1D0 rotate on the first day of every month at
midnight (i.e., the start of the day;
same as @01T00)
$M5D6 rotate on every 5th day of the month at
6:00 hr (same as @05T06)
flags The optional flags field specifies if the archives
should have any special processing done to the archived
log files. The 'Z' flag will make the archive files
compressed to save space using gzip(1) or compress(1),
depending on compilation options. The 'B' flag means
that the file is a binary file, and so the ASCII mes-
sage which newsyslog inserts to indicate the fact that
the logs have been turned over should not be included.
The 'M' flag marks this entry as a monitored log file.
The 'F' flag specifies that symbolic links should be
monitor Specify the username (or email address) that should
receive notification messages if this is a monitored
log file. Notification messages are sent as email; the
operator deserves what they get if they mark the mail
log file as monitored. This field is only valid when
the 'M' flag is set.
pid_file This optional field specifies a file containing the PID
of a process to send a signal (usually SIGHUP) to
instead of /var/run/syslog.pid.
signal Specify the signal to send to the process instead of
SIGHUP. Signal names must start with ``SIG'' and be
the signal name, not the number, e.g., SIGUSR1.
command This optional field specifies a command to run instead
of sending a signal to the process. The command must
be enclosed in double quotes ('"'). The empty string,
'""', can be used to prevent newsyslog from sending a
signal or running a command. You cannot specify both a
command and a PID file. NOTE: If you specify a command
to be run, newsyslog will not send a SIGHUP to
/etc/newsyslog.conf default configuration file
compress(1), gzip(1), syslog(3), syslogd(8)
Theodore Ts'o, MIT Project Athena
Copyright 1987, Massachusetts Institute of Technology
BSD May 29, 2017 BSD