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NEWSYSLOG(8) NetBSD System Manager's Manual NEWSYSLOG(8)
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newsyslog, newsyslog.conf -- maintain system log files to manageable
newsyslog [-Fnrsv] [-f config_file] [file ...]
newsyslog is a program that should be scheduled to run periodically by
cron(8). When it is executed it archives log files if necessary. If a
log file is determined to require archiving, newsyslog rearranges the
files so that ``logfile'' is empty, ``logfile.0'' has the last period's
logs in it, ``logfile.1'' has the next to last period's logs in it and so
on, up to a user-specified number of archived logs. Optionally the
archived logs can be compressed to save space.
A log can be archived for three reasons:
1. It is larger than the configured size (in kilobytes).
2. A configured number of hours have elapsed since the log was
3. The configured time for rotation of the log occurred within
the last 60 minutes.
The granularity of newsyslog is dependent on how often it is scheduled to
run by cron(8). It is recommended that newsyslog be run once hourly.
When starting up, newsyslog reads in a configuration file to determine
which logs may potentially be archived. 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 six mandatory fields and three optional fields, with whitespace
separating each field. Blank lines or lines beginning with `#' are
ignored. The fields of the configuration file are as follows:
Name of the system log file to be archived.
This optional field specifies the owner and group for the ar-
chive file. The `:' is essential, even if the owner or group
field is left blank. The field may be numeric, or a name
which is present in /etc/passwd or /etc/group. For backward
compatibility, `.' is usable in lieu of `:', however use of
this feature is discouraged.
mode Specify the mode of the log file and archives.
ngen Specify the number of archive files to be kept besides the
log file itself.
size When the size of the log file reaches size kilobytes, the log
file will be trimmed as described above. If this field is
replaced by an asterisk (`*'), then the size of the log file
is not taken into account when determining when to trim the
when The when field can consist of an interval, a specific time,
or both. If the when field is an asterisk (`*') log rotation
will depend only on the contents of the size field. Other-
wise, the when field consists of an optional interval in
hours, optionally followed by an `@'-sign and a time in a
restricted ISO 8601 format or by an `$'-sign and a time spec-
ification for logfile rotation at a fixed time once per day,
per week or per month.
If a time is specified, the log file will only be trimmed if
newsyslog is run within one hour of the specified time. If
an interval is specified, the log file will be trimmed if
that many hours have passed since the last rotation. When
both a time and an interval are specified, the log will be
trimmed if either condition is met.
There is no provision for specification of a timezone. There
is little point in specifying an explicit minutes or seconds
component in the current implementation, since the only com-
parison is `within the hour'.
ISO 8601 restricted time format
The lead-in character for a restricted ISO 8601 time is an
`@'-sign. The particular format of the time in restricted
ISO 8601 is: [[[[[cc]yy]mm]dd][T[hh[mm[ss]]]]]. Optional
date fields default to the appropriate component of the cur-
rent date; optional time fields default to midnight; hence if
today is January 22, 1999, the following date specifications
are all equivalent:
Day, week and month time format
The lead-in character for day, week and month specification
is a `$'-sign. The particular format of day, week and month
specification is: [Dhh], [Ww[Dhh]] and [Mdd[Dhh]] respec-
tively. Optional time fields default to midnight. 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 letter `L'
or `l' to specify the last day of the month.
$D0 rotate every night at midnight
$D23 rotate every day at 23:00 hr
$W0D23 rotate every week on Sunday at 23:00 hr
$W5D16 rotate every week on Friday at 16:00 hr
$MLD0 rotate at the last day of every month at mid-
$M5D6 rotate on every 5th day of month at 6:00 hr
flags This field specifies any special processing that is required.
These flags are parsed in a case insensitive manner. Indi-
vidual flags and their meanings:
- This flag means nothing -- it is used as a spacer
when no flags are set.
b The file is a binary file or is not in syslogd(8)
format: the ASCII message which newsyslog inserts to
indicate that the logs have been trimmed should not
c Create an empty log file if none currently exists.
e Do not rotate log file with zero size (empty). This
flag is mostly usable in conjunction with b flag that
prevents newsyslog from inserting an ASCII informa-
j Archived log files should be compressed with bzip2(1)
to save space.
n No signal should be sent when the log is trimmed.
p The first historical log file (i.e. the historical
log file with the suffix `.0') should not be com-
x Archived log files should be compressed with xz(1) to
z Archived log files should be compressed with gzip(1)
to save space.
This optional field specifies the file name to read to find
the daemon process id. If this field is missing, it defaults
to the /var/run/syslogd.pid file. A signal of type sigtype
is sent to the process id contained in this path_to_pid_file
file. This field must start with `/' in order to be recog-
sigtype This optional field specifies the type of signal to be sent
to the daemon process. This may be a numeric or symbolic
value. By default a SIGHUP (hang-up) will be sent.
The following options can be used with newsyslog:
-F Force trimming of the logs, even if the trim conditions have not
been met. This option is useful for diagnosing system problems
by providing you with fresh logs.
Use config_file instead of /etc/newsyslog.conf as the configura-
-n Do not trim the logs, but print out what would be done if this
option were not specified: -n implies -v.
-r Remove the restriction that newsyslog must be running as root.
When running as a regular user, newsyslog will not be able to
send a SIGHUP signal to syslogd(8), so this option should be used
only when debugging or trimming user generated logs.
-s Do not signal daemon processes.
-v Run in verbose mode. In this mode each action that is taken will
If additional command line arguments are given, newsyslog will only exam-
ine log files that match those arguments; otherwise, it will examine all
files listed in the configuration file.
/etc/newsyslog.conf newsyslog configuration file.
bzip2(1), gzip(1), syslog(3), syslogd(8)
NetBSD 9.99 March 1, 2021 NetBSD 9.99