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Manual Pages  — NEWSYSLOG.CONF


newsyslog.confnewsyslog(8) configuration file



The newsyslog.conf file is used to set log file rotation configuration for the newsyslog(8) utility. Configuration may designate that logs are rotated based on size, last rotation time, or time of day. The newsyslog.conf file can also be used to designate secure permissions to log files at rotation time. During initialization, newsyslog(8) reads a configuration file, normally /etc/newsyslog.conf, to determine which logs may potentially be rotated and archived. Each line has five mandatory fields and four optional fields, separated with whitespace. Blank lines or lines beginning with ‘#’ are ignored. If ‘#’ is placed in the middle of the line, the ‘#’ character and the rest of the line after it is ignored. To prevent special meaning, the ‘#’ character may be escaped with ‘\’; in this case preceding ‘\’ is removed and ‘#’ is treated as an ordinary character. The fields of the configuration file are as follows:
  Name of the system log file to be archived, or one of the literal strings "<default>", or "<include>". The special default entry will only be used if a log file name is given as a command line argument to newsyslog(8), and if that log file name is not matched by any other line in the configuration file. The include entry is used to include other configuration files and supports globbing.
owner :group
  This optional field specifies the owner and group for the archive file. The ‘amp;:’ is essential regardless if the owner or group field is left blank or contains a value. The field may be numeric, or a name which is present in /etc/passwd or /etc/group.
mode Specify the file mode of the log file and archives. Valid mode bits are 0666. (That is, read and write permissions for the rotated log may be specified for the owner, group, and others.) All other mode bits are ignored.
count Specify the maximum number of archive files which may exist. This does not consider the current log file.
size When the size of the log file reaches size in kilobytes, the log file will be trimmed as described above. If this field contains an asterisk (‘*’), the log file will not be trimmed based on size.
when The when field may consist of an interval, a specific time, or both. If the when field contains an asterisk (‘*’), log rotation will solely depend on the contents of the size field. Otherwise, the when field consists of an optional interval in hours, usually followed by an 'amp;@ '-sign and a time in restricted ISO 8601 format. Additionally, the format may also be constructed with a ‘$’ sign along with a rotation time specification of once a day, once a week, or once a month.

Time based trimming happens only if newsyslog(8) 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 then both conditions must be satisfied for the rotation to take place.

There is no provision for the 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: [D hh], [W w[D hh]], and [M dd[D hh]], 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 one of the letters ‘L’ or ‘l’ to specify the last day of the month.

Some examples:

$D0 rotate every night at midnight (same as @T00)
$D23 rotate every day at 23:00 (same as @T23)
$W0D23 rotate every week on Sunday at 23:00
$W5D16 rotate every week on Friday at 16:00
$M1D0 rotate at the first day of every month at midnight (i.e., the start of the day; same as @01T00)
$M5D6 rotate on every fifth day of month at 6:00 (same as @05T06)
flags This optional field is made up of one or more characters that specify any special processing to be done for the log files matched by this line. The following are valid flags:
B indicates that the log file is a binary file, or has some special format. Usually newsyslog(8) inserts an ASCII message into a log file during rotation. This message is used to indicate when, and sometimes why the log file was rotated. If B is specified, then that informational message will not be inserted into the log file.
C indicates that the log file should be created if it does not already exist, and if the -C option was also specified on the command line.
D indicates that newsyslog(8) should set the UF_NODUMP flag when creating a new version of this log file. This option would affect how the dump(8) command treats the log file when making a file system backup.
E indicates that the log file should not be rotated when its size is zero. The E flag is mostly useful in conjunction with B flag to prevent newsyslog(8) from inserting an informational ASCII message into the new file.
G indicates that the specified logfile_name is a shell pattern, and that newsyslog(8) should archive all filenames matching that pattern using the other options on this line. See glob(3) for details on syntax and matching rules.
J indicates that newsyslog(8) should attempt to save disk space by compressing the rotated log file using bzip2(1).
N indicates that there is no process which needs to be signaled when this log file is rotated.
p indicates that the zero-th rotated file should not be compressed.
R if this flag is set the newsyslog(8) will run shell command defined in path_to_pid_cmd_file after rotation instead of trying to send signal to a process id stored in the file.
T if this flag is set the informational rotation message written to the log file will be in the format specified by RFC5424. Normally, the rotation message is written in the traditional (RFC3164) syslog format.
U indicates that the file specified by path_to_pid_cmd_file will contain the ID for a process group instead of a process. This option also requires that the first line in that file be a negative value to distinguish it from a process ID.
X indicates that newsyslog(8) should attempt to save disk space by compressing the rotated log file using xz(1).
Y indicates that newsyslog(8) should attempt to save disk space by compressing the rotated log file using zstd(1).
Z indicates that newsyslog(8) should attempt to save disk space by compressing the rotated log file using gzip(1).
- a minus sign will not cause any special processing, but it can be used as a placeholder to create a flags field when you need to specify any of the following fields.
  This optional field specifies the file name containing a daemon's process ID or to find a group process ID if the U flag was specified. If this field is present, a signal is sent to the process ID contained in this file. If this field is not present and the N flag has not been specified, then a SIGHUP signal will be sent to syslogd(8) or to the process id found in the file specified by newsyslog(8)'s -S switch. This field must start with ‘/’ in order to be recognized properly. When used with the R flag, the file is treated as a path to a binary to be executed by the newsyslog(8) after rotation instead of sending the signal out.
  This optional field specifies the signal that will be sent to the daemon process (or to all processes in a process group, if the U flag was specified). If this field is not present, then a SIGHUP signal will be sent. Signal names must start with "SIG" and be the signal name, e.g., SIGUSR1. Alternatively, signal can be the signal number, e.g., 30 for SIGUSR1.


The following is an example of the "<include>" entry:

    <include> /etc/newsyslog-local.conf


bzip2(1), gzip(1), xz(1), syslog(3), chown(8), newsyslog(8), syslogd(8)

C. Lonvick, RFC3164, The BSD syslog Protocol,

R. Gerhards, RFC5424, The Syslog Protocol,


This manual page first appeared in FreeBSD 4.10 .

NEWSYSLOG.CONF (5) February 26, 2021

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