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 last archived.
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:
logfile_name
Name of the system log file to be archived.
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 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 log file.
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 format or by an ‘
$'-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, 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 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 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]] respectively. Optional time fields default to midnight. The ranges for day and hour specifications are:
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.
Some examples:
$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 save space.
z
Archived log files should be compressed with
gzip(1) to save space.
path_to_pid_file
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.
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.