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S3QLLOCK(1)			     S3QL			   S3QLLOCK(1)

       s3qllock	- Make trees on	an S3QL	file system immutable

	  s3qllock [options] <directory>

       S3QL  is	a file system for online data storage. Before using S3QL, make
       sure to consult the full	documentation (rather than just	the man	 pages
       which only briefly document the available userspace commands).

       The  s3qllock command makes a directory tree in an S3QL file system im-
       mutable.	Immutable trees	can no longer be changed in  any  way  whatso-
       ever.  You  can not add new files or directories	and you	can not	change
       or delete existing files	and directories. The only way to get rid of an
       immutable tree is to use	the s3qlrm command.

       s3qllock	 can  only  be called by the user that mounted the file	system
       and (if the file	system was mounted with	--allow-other or --allow-root)
       the root	user.

       Immutability  is	a feature designed for backups.	Traditionally, backups
       have been made on external tape drives. Once a  backup  was  made,  the
       tape  drive  was	 removed and locked somewhere in a shelf. This has the
       great advantage that the	contents of the	 backup	 are  now  permanently
       fixed.  Nothing	(short	of  physical destruction) can change or	delete
       files in	the backup.

       In contrast, when backing up into an online storage system  like	 S3QL,
       all backups are available every time the	file system is mounted.	 Noth-
       ing prevents a file in an old backup from being changed again later on.
       In  the	worst case, this may make your entire backup system worthless.
       Imagine that your system	gets infected by a  nasty  virus  that	simply
       deletes	all  files  it	can  find  -- if the virus is active while the
       backup file system is mounted, the virus	 will  destroy	all  your  old
       backups as well!

       Even  if	 the  possibility  of a	malicious virus	or trojan horse	is ex-
       cluded, being able to change a backup after it has been made is	gener-
       ally not	a good idea. A common S3QL use case is to keep the file	system
       mounted at all times and	periodically create  backups  with  rsync  -a.
       This  allows every user to recover her files from a backup without hav-
       ing to call the system administrator. However, this also	 allows	 every
       user to accidentally change or delete files in one of the old backups.

       Making a	backup immutable protects you against all these	problems.  Un-
       less you	happen to run into a virus that	was specifically programmed to
       attack  S3QL  file  systems, backups can	be neither deleted nor changed
       after they have been made immutable.

       The s3qllock command accepts the	following options:

	  --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.

		 Activate debugging output from	all S3QL modules.  Debug  mes-
		 sages	will  be  written to the target	specified by the --log

		 be really quiet

		 just print program version and	exit

       s3qllock	may terminate with the following exit codes:

       0      Everything went well.

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

       2      Invalid command line argument.

       The S3QL	homepage is at

       The  full S3QL documentation should also	be installed somewhere on your
       system,	common	 locations   are   /usr/share/doc/s3ql	 or   /usr/lo-

       A(C) 2008 Nikolaus Rath <>

2.21			       October 28, 2016			   S3QLLOCK(1)


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