logadm(1M) System Administration Commands logadm(1M)
logadm - manage endlessly growing log files
logadm [-options] logname...
logadm is a general log rotation tool that is suitable for running from cron(1M).
Without arguments, logadm reads the /etc/logadm.conf file, and for every entry found in that file checks the corresponding log file to see
if it should be rotated. Typically this check is done each morning by an entry in the root's crontab.
If the logname argument is specified, logadm renames the corresponding log file by adding a suffix so that the most recent log file ends
with .0 (that is, logfile.0), the next most recent ends with .1 (that is, logfile.1), and so forth. By default, ten versions of old log
files are kept (that is, logfile.0 through logfile.9) and logadm automatically deletes the oldest version when appropriate to keep the
count of files at ten.
logadm takes a number of options. You can specify these options on the command line or in the /etc/logadm.conf file. The logadm command
searches /etc/logadm.conf for lines of the form logname options
logname Identifies the name of the entry in /etc/logadm.conf, but if no log file name is given in that entry it is assumed
that the logname is the same as the actual log file name.
options Identifies command line options exactly as they would be entered on the command line. This allows commonly used log
rotation policies to be stored in the /etc/logadm.conf file. See EXAMPLES.
If options are specified both in /etc/logadm.conf and on the command line, those in the /etc/logadm.conf file are
applied first. Therefore, the command line options override those in /etc/logadm.conf.
Log file names specified in /etc/logadm.conf may contain filename substitution characters such as * and ?, that are
supported by csh(1).
Two options control when a log file is rotated. They are: -s size -p period.
When using more than one of these options at a time, there is an implied and between them. This means that all conditions must be met
before the log is rotated.
If neither of these two options are specified, the default conditions for rotating a log file are: -s 1b -p 1w, which means the log file is
only rotated if the size is non-zero and if at least 1 week has passed since the last time it was rotated.
By specifying -p never as a rotation condition, any other rotation conditions are ignored and logadm moves on to the expiration of old log
files. By specifying -p now as a rotation condition, a log rotation is forced.
Unless specified by the -o, -g, or -m options, logadm replaces the log file (after renaming it) by creating an empty file whose owner,
group ID, and permissions match the original file.
Three options control when old log files are expired: -A age -C count -Ssize. These options expire the oldest log files until a particular
condition or conditions are met. For example, the combination -C 5 and the -S 10m options expires old log files until there are no more
than 5 of the and their combined disk usage is no more than 10 megabytes. If none of these options are specified, the default expiration is
-C 10 which keeps ten old log files. If no files are to be expired, use -C 0 to prevent expiration by default.
The following options are supported:
-a post_command Execute the post_command after renaming the log file. post_command is passed to sh -c.
Specify post_command as a valid shell command. Use quotes to protect spaces or shell metacharacters in post_command.
This option can be used to restart a daemon that is writing to the file. When rotating multiple logs with one logadm com-
mand, post_command is executed only once after all the logs are rotated, not once per rotated log.
-A age Delete any versions that have not been modified for the amount of time specified by age.
Specify age as a number followed by an h (hours), d (days), w(weeks), m (months), or y (years).
-b pre_command Execute pre_command before renaming the log file. pre_command is passed to sh -c.
Specify pre_command as a valid shell command. Use quotes to protect spaces or shell metacharacters in the pre_command.
This option can be used to stop a daemon that is writing to the file. When rotating multiple logs with one logadm command,
pre_command is executed only once before all the logs are rotated, not once per rotated log.
-c Rotate the log file by copying it and truncating the original logfile to zero length, rather than renaming the file.
-C count Delete the oldest versions until there are not more than count files left.
If no expire options (-A, -C, or -S) are specified, -C 10 is the default. To prevent the default expire rule from being
added automatically, specify -C 0 .
-e mail_addr Send error messages by email to mail_addr.
As logadm is typically run from cron(1M), error messages are captured by cron and mailed to the owner of the crontab.
This option is useful you want the mail regarding error messages to go to another address instead. If no errors are encoun-
tered, no mail message is generated.
-E cmd Execute cmd to expire the file, rather than deleting the old log file to expire it.
cmd is passed it to sh -c. The file is considered expired after cmd completes. If the old log file is not removed or
renamed by the cmd, logadm considers it for expiration the next time that it runs on the specified log file. If present,
the keyword $file is expanded in the specified cmdto the name of the file being expired.
This option is useful for tasks such as mailing old log files to administrators, or copying old log files to long term
-f conf_file Use conf_file instead of /etc/logadm.conf.
This option allows non-root users to keep their own logadm configuration files.
-g group Create a new empty file with the ID specified by group, instead of preserving the group ID of the log file.
Specify group by name or by numeric group ID, as accepted by chgrp(1).
This option requires the ability to change file group ownership using the chgrp(1) command.
-h Print a help message that describes logadm's options.
-m mode Create a new empty file with the mode specified by mode, instead of preserving the mode of the log file.
Specify mode in any form that is accepted by the chmod(1) command.
-M cmd Use cmd to rename the log file. If the keyword $file is specified, it is expanded to the name of the log file. Similarly,
the keyword $nfile is expanded to the new name of the log file. The $nfile keyword is only available with commands provided
with the -M option. After the command completes, the log file is replaced by the rotate file. The default cmd is "/bin/mv
-n Print the actions that the logadm command will perform without actually performing them.
This option is useful for checking arguments before making any changes to the system.
It is important to remember, however, that since log rotating actions are only printed with this option, logadm might not
find files that need expiring, but if run without the -n logadm might create a file that needs expiring by performing the
log rotating actions. Therefore, if you see no files being expired with the -n option, files still might be expired without
-N Prevent an error message if the specified logfile does not exist. Normally, logadm produces an error message if the log
file is not found. With -N, if the log file doesn't exist logadm moves on to the expire rules (if any) and then to the next
log file (if any), without creating the empty replacement log file.
-o owner Create the new empty file with owner, instead of preserving the owner of the log file.
Specify owner in any form that is accepted by the chown(1) command.
-p period Rotate a log file after the specified time period (period) .
Specify period as a number followed by d for days, h for hours, w for weeks, m for months (really 30 days) or y for years.
There are also two special values for period: now and never. -p now forces log rotation. -p never forces no log rotation.
-P timestamp Used by logadm to record the last time the log was rotated in /etc/logadm.conf.
This option uses timestamp to determine if the log rotation period has passed. The format of timestamp matches the format
generated by ctime(3C), with quotes around it to protect embedded spaces. timestamp is always recorded in the Coordinated
Universal Time (UTC) timezone.
-r Remove any entries corresponding to the specified logname from the /etc/logadm.conf.
-R cmd Run the cmd when an old log file is created by a log rotation. If the keyword $file is embedded in the specified command,
it is expanded to the name of the old log file just created by log rotation.
This option is useful for processing log file contents after rotating the log. cmd is executed by passing it to sh -c. When
rotating multiple logs with one logadm command, the command supplied with -R is executed once every time a log is rotated.
This is useful for post-processing a log file (that is, sorting it, removing uninteresting lines, etc.). The -a option is a
better choice for restarting daemons after log rotation.
-s size Rotate the log file only if its size is greater than or equal to size.
Specify size as a number followed by the letter b for bytes, k for kilobytes, m for megabytes, or g for gigabytes.
-S size Delete the oldest versions until the total disk space used by the old log files is less than the specified size.
Specify size as a number followed by the letter b for bytes, k for kilobytes, m for megabytes, or g for gigabytes.
-t template Specify the template to use when renaming log files.
template can be a simple name, such as /var/adm/oldfile, or it can contain special keywords which are expanded by logadm
and are in the form $word. Allowed sequences are:
$file The full path name of the file to be rotated
$dirname The directory of the file to be rotated
$basename The log file name, without the directory name
$n The version number, 0 is most recent, 1 is next most recent, and so forth
$N The same as $n, but starts at 1 instead of zero
$secs The number of seconds since 00:00:00 UTC, January 1,1970
$nodename Expands to the output of uname -n
$platform Expands to the output of uname -i
$isa Expands to the output of uname -p
$release Expands to the output of uname -r
$machine Expands to the output of uname -m
$domain Expands to the output of domainname
To actually have the dollar sign character in the file name, use $$. Any percent sequences allowed by strftime(3C) are also
allowed, for example, %d expands to the day of the month. To actually have a percent sign character in the file name, use
%%. Both dollar-sign keywords and percent sequences can appear anywhere in the template. If the template results in a path-
name with non-existent directories, they are created as necessary when rotating the log file.
If no -toption is specified, the default template is $file.$n. Actual rotation of log files, where each version is shifted
up until it expires is done using the $n keyword. If the template does not contain the $n keyword, the log file is simply
renamed to the new name and then the expire rules, if any, are applied.
-T pattern Normally logadm looks for a list of old log files by turning the template (specified with the -t option) into a pattern and
finding existing files whose names match that pattern. The -T option causes the given pattern to be used instead.
This option is useful if another program fiddles with the old log file names, like a cron job to compress them over time.
The pattern is in the form of a pathname with special characters such as * and ? as supported by csh(1) filename substitu-
-v Print information about the actions being executed in verbose mode.
-V Validate the configuration file.
This option validates that an entry for the specified logname exists in the /etc/logadm.conf file and is syntactically cor-
rect. If logname is not specified, all entries in the configuration file are validated. If a logname argument is specified,
the command validates the syntax of that entry. If the entry is found, it is printed and the exit value of the command is
true. Otherwise the exit value is false.
-w entryname Write an entry into the config file (that is, /etc/logadm.conf) which corresponds to the current command line arguments. If
an entry already existed for the specified entryname, it is removed first. This is the preferred method for updating
/etc/logadm.conf since using it prevents syntax errors in that file. The entryname is the name of the entry in
/etc/logadm.conf, and that name can be used as the "logname" argument to future calls to logadm to take advantage of that
entry. The entryname can be chosen to be something that is easy to specify, or it can be the actual log file name. If no
log file name is provided on the command line, the entry name is assumed to be the same as the log file name. For example,
the following two lines achieve the same thing, keeping two copies of rotated log files, but the first example names the
entry something easier to enter on the command line:
% logadm -C2 -w mylog /my/really/long/log/file/name
% logadm -C2 -w /my/really/long/log/file/name
-z count Compress old log files as they are created. count of the most recent log files are left uncompressed, therefore making the
count most recent files easier to peruse. Use count of zero to compress all old logs.
The compression is done with gzip(1) and the resulting log file has the suffix of .gz.
The following operands are supported:
logname Identifies the name of the entry in /etc/logadm.conf. If the log file name is specified in the logname field, it
is assumed that logname is the same as the actual log file name.
Example 1: Rotating a File and Keeping Previous Versios
The following example rotates the /var/adm/exacct/proc file, keeping ten previous versions in /var/adm/exacct/proc.0 through
Tell logadm to copy the file and truncate it.
% logadm -c /var/adm/exacct/proc
Example 2: Rotating syslog
The following example rotates syslog and keeps eight log files. Old log files are put in the directory /var/oldlogs instead of /var/log:
% logadm -C8 -t'/var/oldlogs/syslog.$n' /var/log/syslog
Example 3: Rotating /var/adm/sulog and Expiring Based on Age
The following entry in the /etc/logadm.conf file rotates the /var/adm/sulog file and expires any copies older than 30 days.
/var/adm/sulog -A 30d
Example 4: Rotating Files and Expiring Based on Disk Usage
The following entry in the /etc/logadm.conf file rotates the /var/adm/sulog file and expires old log files when more than 100 megabytes are
used by the sum of all the rotated log files.
/var/adm/sulog -S 100m
Example 5: Creating an Entry that Stores the Logfile Name
This example creates an entry storing the log file name and the fact that we want to keep 20 copies in /etc/logadm.conf, but the -p never
means the entry is ignored by the normal logadm run from root's crontab every morning.
% logadm -w locallog /usr/local/logfile -C20 -p never
Use the following entry on the command line to override the -p never option:
% logadm -p now locallog
Example 6: Rotating the apache Error and Access Logs
The following example rotates the apache error and access logs monthly to filenames based on current year and month. It keeps the 24 most
recent copies and tells apache to restart after renaming the logs.
This command is run once, and since the -w option is specified, an entry is made in /etc/logadm.conf so the apache logs are rotated from
% logadm -w apache -p 1m -C 24
-a '/usr/apache/bin/apachectl graceful'
This example also illustrates that the entry name supplied with the -w option doesn't have to match the log file name. In this example, the
entry name is apache and once the line has been run, the entry in /etc/logadm.conf can be forced to run by executing the following command:
% logadm -p now apache
Because the expression matching the apache log file names was enclosed in quotes, the expression is stored in /etc/logadm.conf, rather than
the list of files that it expands to. This means that each time logadm runs from cron it expands that expression and checks all the log
files in the resulting list to see if they need rotating.
The following command is an example without the quotes around the log name expression. The shell expands the last argument into a list of
log files that exist at the time the command is entered, and writes an entry to /etc/logadm.conf that rotates the files.
logadm -w apache /var/apache/logs/*_log
/etc/logadm.conf configuration file for logadm command
See attributes(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|Availability |SUNWcsu |
chgrp(1), chmod(1), chown(1), csh(1), gzip(1), cron(1M), ctime(3C), strftime(3C), logadm.conf(4), attributes(5)
When logadm applies expire conditions (supplied by the -A, -C, and -S options), it deletes files, the oldest first, until the conditions
are satisfied. If the template used for naming the old logs contained $n or $N, logadm picks the highest value of $n or $N found in the old
log file names first. If the template used is something else, logadm uses the modification time to determine which files to expire first.
This may not be the expected behavior if an old log file has been modified since it was rotated.
SunOS 5.10 1 Dec 2004 logadm(1M)