The mount.s3ql command


mount.s3ql [options] <storage url> <mount point>


The mount.s3ql command mounts the S3QL file system stored in storage url in the directory mount point. The format of the storage url depends on the backend that is used. The S3QL User’s Guide should be consulted for a description of the available backends.


The mount.s3ql command accepts the following options.

--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: ~/.s3ql/mount.log

--cachedir <path>

Store cached data in this directory (default: ~/.s3ql)

--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

--backend-options <options>

Backend specific options (separate by commas). See backend documentation for available options.


just print program version and exit

--authfile <path>

Read authentication credentials from this file (default: ~/.s3ql/authinfo2)

--compress <algorithm-lvl>

Compression algorithm and compression level to use when storing new data. algorithm may be any of lzma, bzip2, zlib, or none. lvl may be any integer from 0 (fastest) to 9 (slowest). Default: lzma-6

--cachesize <size>

Cache size in KiB (default: autodetect).

--max-cache-entries <num>

Maximum number of entries in cache (default: autodetect). Each cache entry requires one file descriptor, so if you increase this number you have to make sure that your process file descriptor limit (as set with ulimit -n) is high enough (at least the number of cache entries + 100).


Do not purge locally cached files on exit.


Normally, only the user who called mount.s3ql can access the mount point. This user then also has full access to it, independent of individual file permissions. If the --allow-other option is specified, other users can access the mount point as well and individual file permissions are taken into account for all users.


Like --allow-other, but restrict access to the mounting user and the root user.

--dirty-block-upload-delay <seconds>

Upload delay for dirty blocks in seconds (default: 10 seconds).


Do not daemonize, stay in foreground

--fs-name FS_NAME

Mount name passed to fuse, the name will be shown in the first column of the system mount command output. If not specified your storage url is used.


Run as systemd unit. Consider specifying –log none as well to make use of journald.

--metadata-backup-interval <seconds>

Interval between metadata backups. Should the filesystem crash while mounted, modifications made after the most recent metadata backup may be lost. During backups, the filesystem will be unresponsile. Default: 6h

--threads <no>

Number of parallel upload threads to use (default: auto).


Enable some optimizations for exporting the file system over NFS. (default: False)

Exit Codes

mount.s3ql 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.


Invalid backend option.


Could not open log file for writing.


No such backend.


Authentication file has insecure permissions.


Unable to parse proxy settings.


Invalid credentials (Authentication failed).


No permission to access backend (Authorization denied).


Invalid storage URL, specified location does not exist in backend.


Wrong file system passphrase.


No S3QL file system found at given storage URL.


Unable to connect to backend, can’t resolve hostname.


File system was not unmounted cleanly.


File system appears to be mounted elsewhere.


Unsupported file system revision (too old).


Unsupported file system revision (too new).


Insufficient free nodes, need to run fsck.s3ql.


Attempted to mount read-only, this is not supported.


Mountpoint does not exist.


Not enough available file descriptors.


Unable to bind file system to mountpoint.


Unable to access cache directory.

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.