The s3qlctrl command


s3qlctrl [options] <action> <mountpoint> ...

where action may be either of flushcache, dropcache, log, cachesize or backup-metadata.


The s3qlctrl command performs various actions on the S3QL file system mounted in mountpoint.

s3qlctrl 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.

The following actions may be specified:


Write all modified blocks to the backend. The command blocks until the cache is clean.


Flush the filesystem cache and then drop all contents (i.e., make the cache empty).


Change the amount of information that is logged. The complete syntax is:

s3qlctrl [options] log <mountpoint> <level> [<module> ...]

here level is the desired new log level and may be either of debug, info or warn. One or more module may only be specified with the debug level and allow to restrict the debug output to just the listed modules.


Changes the cache size of the file system. This action requires an additional argument that specifies the new cache size in KiB, so the complete command line is:

s3qlctrl [options] cachesize <mountpoint> <new-cache-size>

Trigger a metadata backup.


The s3qlctrl command also accepts the following options, no matter what specific action is being invoked:

--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, ‘all’ for everything). Debug messages will be written to the target specified by the --log option.


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


be really quiet


just print program version and exit

Hint: run s3qlctrl <action> --help to get help on the additional arguments that the different actions take.

Exit Codes

s3qlctrl may terminate with the following exit codes:


Everything went well.


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


Invalid command line argument or configuration file key.

See Also

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/local/doc/s3ql.