rotatelogs - Piped logging program to rotate Apache logs (2024)

rotatelogs is a simple program for use in conjunction with Apache's piped logfile feature. It supports rotation based on a time interval or maximum size of the log.

• Synopsis
• Options
• Examples
• Portability

See also

• Comments

Synopsis

rotatelogs [ -l ] [ -L linkname ] [ -p program ] [ -f ] [ -D ] [ -t ] [ -v ] [ -e ] [ -c ] [ -n number-of-files ] logfile rotationtime|filesize(B|K|M|G) [ offset ]

Options

-l

Causes the use of local time rather than GMT as the base for theinterval or for strftime(3) formatting with size-basedrotation.

-L linkname

Causes a hard link to be made from the current logfileto the specified link name. This can be used to watchthe log continuously across rotations using a command liketail -F linkname.

If the linkname is not an absolutepath, it is relative to rotatelogs' working directory,which is the ServerRoot whenrotatelogs is run by the server.

-p program

If given, rotatelogs will execute the specifiedprogram every time a new log file is opened. The filename of thenewly opened file is passed as the first argument to the program. Ifexecuting after a rotation, the old log file is passed as the secondargument. rotatelogs does not wait for the specifiedprogram to terminate before continuing to operate, and will not logany error code returned on termination. The spawned program uses thesame stdin, stdout, and stderr as rotatelogs itself, and also inheritsthe environment.

-f

Causes the logfile to be opened immediately, as soon asrotatelogs starts, instead of waiting for thefirst logfile entry to be read (for non-busy sites, there may bea substantial delay between when the server is startedand when the first request is handled, meaning that theassociated logfile does not "exist" until then, whichcauses problems from some automated logging tools)

-D

Creates the parent directories of the path that the log file will beplaced in if they do not already exist. This allows strftime(3)formatting to be used in the path and not just the filename.

-t

Causes the logfile to be truncated instead of rotated. This isuseful when a log is processed in real time by a command like tail,and there is no need for archived data. No suffix will be added tothe filename, however format strings containing '%' characterswill be respected.

-T

Causes all but the initial logfile to be truncated when opened.This is useful when the format string contains something that willloop around, such as the day of the month. Available in 2.4.56 and later.

-v

Produce verbose output on STDERR. The output containsthe result of the configuration parsing, and all file open andclose actions.

-e

Echo logs through to stdout. Useful when logs need to be furtherprocessed in real time by a further tool in the chain.

-c

Create log file for each interval, even if empty.

-n number-of-files

Use a circular list of filenames without timestamps. This option overwrites log files at startup and during rotation. With -n 3, the series of log files opened would be "logfile", "logfile.1", "logfile.2", then overwriting "logfile".
When this program first opens "logfile", the file will only be truncated if -t is also provided. Every subsequent rotation willalways begin with truncation of the target file. For size based rotation without -t and existing log files in place,this option may result in unintuitive behavior such as initial log entries being sent to "logfile.1", and entries in "logfile.1" not being preservedeven if later "logfile.n" have not yet been used.
Available in 2.4.5 and later.

logfile

The path plus basename of the logfile. If logfileincludes any '%' characters, it is treated as a format string forstrftime(3). Otherwise, the suffix.nnnnnnnnnn is automatically added and is the time inseconds (unless the -t option is used). Both formats compute thestart time from the beginning of the current period. For example,if a rotation time of 86400 is specified, the hour, minute, andsecond fields created from the strftime(3) format willall be zero, referring to the beginning of the current 24-hourperiod (midnight).

When using strftime(3) filename formatting,be sure the log file format has enough granularity to producea different file name each time the logs are rotated. Otherwiserotation will overwrite the same file instead of starting a newone. For example, if logfile was/var/log/errorlog.%Y-%m-%d with log rotation at 5megabytes, but 5 megabytes was reached twice in the same day, thesame log file name would be produced and log rotation would keepwriting to the same file.

If the logfile is not an absolutepath, it is relative to rotatelogs' working directory,which is the ServerRoot whenrotatelogs is run by the server.

See Also

Understanding the Apache Access Log: View, Locate and Analyze | Sumo Logic

rotationtime

The time between log file rotations in seconds. The rotationoccurs at the beginning of this interval. For example, if therotation time is 3600, the log file will be rotated at the beginningof every hour; if the rotation time is 86400, the log file will berotated every night at midnight. (If no data is logged during aninterval, no file will be created.)

filesize(B|K|M|G)

The maximum file size in followed by exactly one of the lettersB (Bytes), K (KBytes), M (MBytes)or G (GBytes).

When time and size are specified, the size must be given after the time.Rotation will occur whenever either time or size limits are reached.

offset

The number of minutes offset from UTC. If omitted, zero isassumed and UTC is used. For example, to use local time in the zoneUTC -5 hours, specify a value of -300 for this argument.In most cases, -l should be used instead of specifyingan offset.

Examples

CustomLog "|bin/rotatelogs /var/log/logfile 86400" common

This creates the files /var/log/logfile.nnnn where nnnn is the system time at which the log nominally starts (this time will always be a multiple of the rotation time, so you can synchronize cron scripts with it). At the end of each rotation time (here after 24 hours) a new log is started.

CustomLog "|bin/rotatelogs -l /var/log/logfile.%Y.%m.%d 86400" common

This creates the files /var/log/logfile.yyyy.mm.dd where yyyy is the year, mm is the month, and dd is the day of the month. Logging will switch to a new file every day at midnight, local time.

CustomLog "|bin/rotatelogs /var/log/logfile 5M" common

This configuration will rotate the logfile whenever it reaches a size of 5 megabytes.

ErrorLog "|bin/rotatelogs /var/log/errorlog.%Y-%m-%d-%H_%M_%S 5M"

This configuration will rotate the error logfile whenever it reaches a size of 5 megabytes, and the suffix to the logfile name will be created of the form errorlog.YYYY-mm-dd-HH_MM_SS.

CustomLog "|bin/rotatelogs -t /var/log/logfile 86400" common

This creates the file /var/log/logfile, truncating the file at startup and then truncating the file once per day. It is expected in this scenario that a separate process (such as tail) would process the file in real time.

CustomLog "|bin/rotatelogs -T /var/log/logfile.%d 86400" common

If the server is started (or restarted) on the first of the month, this appends to /var/log/logfile.01. When a log entry is written on thesecond of the month, /var/log/logfile.02 is truncated and new entrieswill be added to the top. This example keeps approximately 1 months worth of logs without external maintenance.

Portability

The following logfile format string substitutions should besupported by all strftime(3) implementations, seethe strftime(3) man page for library-specificextensions.