Provided by: s3ql_3.3.2+dfsg-1ubuntu1_amd64 bug

NAME

       expire_backups - Intelligently expire old backups

SYNOPSIS

          expire_backups [options] <age> [<age> ...]

DESCRIPTION

       The expire_backups command intelligently remove old backups that are no longer needed.

       To  define  what backups you want to keep for how long, you define a number of age ranges.
       expire_backups ensures that you will have at least one backup in each  age  range  at  all
       times.  It  will  keep  exactly  as  many  backups as are required for that and delete any
       backups that become redundant.

       Age ranges are specified by giving a list of range boundaries in terms of  backup  cycles.
       Every time you create a new backup, the existing backups age by one cycle.

       Example:  when expire_backups is called with the age range definition 1 3 7 14 31, it will
       guarantee that you always have the following backups available:

       1. A backup that is 0 to 1 cycles old (i.e, the most recent backup)

       2. A backup that is 1 to 3 cycles old

       3. A backup that is 3 to 7 cycles old

       4. A backup that is 7 to 14 cycles old

       5. A backup that is 14 to 31 cycles old

       NOTE:
          If you do backups in fixed intervals, then one cycle will be equivalent to  the  backup
          interval.  The  advantage of specifying the age ranges in terms of backup cycles rather
          than days or weeks is  that  it  allows  you  to  gracefully  handle  irregular  backup
          intervals.   Imagine  that  for  some  reason  you do not turn on your computer for one
          month. Now all your backups are at least a month old, and  if  you  had  specified  the
          above  backup strategy in terms of absolute ages, they would all be deleted! Specifying
          age ranges in terms of backup cycles avoids these sort of problems.

       expire_backups usage is simple. It requires backups to be stored  in  directories  of  the
       form  year-month-day_hour:minute:seconds (YYYY-MM-DD_HH:mm:ss) and works on all backups in
       the current directory. So for the above backup strategy, the correct invocation would be:

          expire_backups.py 1 3 7 14 31

       When storing your backups on an S3QL  file  system,  you  probably  want  to  specify  the
       --use-s3qlrm option as well. This tells expire_backups to use the s3qlrm command to delete
       directories.

       expire_backups uses a "state file" to keep track which backups are  how  many  cycles  old
       (since  this  cannot  be  inferred  from  the dates contained in the directory names). The
       standard name for this state file is .expire_backups.dat. If this  file  gets  damaged  or
       deleted,  expire_backups  no  longer knows the ages of the backups and refuses to work. In
       this case you can use the --reconstruct-state option to try to reconstruct the state  from
       the  backup  dates.  However,  the accuracy of this reconstruction depends strongly on how
       rigorous you have been with making backups (it is only  completely  correct  if  the  time
       between  subsequent  backups  has  always been exactly the same), so it's generally a good
       idea not to tamper with the state file.

OPTIONS

       The expire_backups command accepts the following options:

          --quiet
                 be really quiet

          --log <target>
                 Destination for log messages. Specify none for standard output or syslog for the
                 system  logging  daemon.  Anything  else will be interpreted as a file name. Log
                 files will be rotated when they reach 1 MiB, and at most 5 old log files will be
                 kept. Default: None

          --debug-modules <modules>
                 Activate  debugging  output  from  specified  modules  (use  commas  to separate
                 multiple modules). Debug messages will be written to the target specified by the
                 --log option.

          --debug
                 Activate  debugging output from all S3QL modules. Debug messages will be written
                 to the target specified by the --log option.

          --version
                 just print program version and exit

          --state <file>
                 File to save state information in (default: ".expire_backups.dat")

          -n     Dry run. Just show which backups would be deleted.

          --reconstruct-state
                 Try to reconstruct a missing state file from backup dates.

          --use-s3qlrm
                 Use s3qlrm command to delete backups.

EXIT CODES

       expire_backups may terminate with the following exit codes:

       0      Everything went well.

       1      An unexpected error occured. This may indicate a bug in the program.

       2      Invalid command line argument or configuration file key.

SEE ALSO

       expire_backups is shipped as part of S3QL, https://github.com/s3ql/s3ql/.

COPYRIGHT

       © 2008 Nikolaus Rath <Nikolaus@rath.org>