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NEWSYSLOG(8) NetBSD System Manager's Manual NEWSYSLOG(8)
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newsyslog -- maintain system log files to manageable sizes
newsyslog [-nrsvF] [-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 archive
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 compatibil-
ity, ``.'' is usable in lieu of ``:'', however use of this fea-
ture 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
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 log
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. Otherwise, the
when field consists of an optional interval in hours, optionally
followed by an `@'-sign and a time in a restricted ISO 8601 for-
mat or by an `$'-sign and a time specification for logfile rota-
tion at a fixed time once per day, per week or per month.
If a time is specified, the log file will only be trimmed if
newsyslog is run within one hour of the specified time. If an
interval is specified, the log file will be trimmed if that many
hours have passed since the last rotation. When both a time and
an interval are specified, the log will be trimmed if either con-
dition is met.
There is no provision for specification of a timezone. There is
little point in specifying an explicit minutes or seconds compo-
nent in the current implementation, since the only comparison is
`within the hour'.
ISO 8601 restricted time format
The lead-in character for a restricted ISO 8601 time is an
`@'-sign. The particular format of the time in restricted ISO
8601 is: [[[[[cc]yy]mm]dd][T[hh[mm[ss]]]]]. Optional date fields
default to the appropriate component of the current date;
optional time fields default to midnight; hence if today is Jan-
uary 22, 1999, the following date specifications are all equiva-
Day, week and month time format
The lead-in character for day, week and month specification is a
`$'-sign. The particular format of day, week and month specifi-
cation is: [Dhh], [Ww[Dhh]] and [Mdd[Dhh]] respectively.
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 midnight
$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. Individual
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 be included.
c Create an empty log file if none currently exists.
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 compressed.
j Archived log files should be compressed with bzip2(1) to
x Archived log files should be compressed with xz(1) to
z Archived log files should be compressed with gzip(1) to
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 recognized properly.
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:
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 HUP 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
-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.
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 7.0 June 16, 2012 NetBSD 7.0