NAME

       mkfs.cramfs - make compressed ROM file system

SYNOPSIS

       mkfs.cramfs [options] directory file

DESCRIPTION

       Files on cramfs file systems are zlib-compressed one page at a time to allow random read
       access. The metadata is not compressed, but is expressed in a terse representation that is
       more space-efficient than conventional file systems.

       The file system is intentionally read-only to simplify its design; random write access for
       compressed files is difficult to implement. cramfs ships with a utility (mkcramfs(8)) to
       pack files into new cramfs images.

       File sizes are limited to less than 16 MB.

       Maximum file system size is a little under 272 MB. (The last file on the file system must
       begin before the 256 MB block, but can extend past it.)

ARGUMENTS

       The directory is simply the root of the directory tree that we want to generate a
       compressed filesystem out of.

       The file will contain the cram file system, which later can be mounted.

OPTIONS

       -v
           Enable verbose messaging.

       -E
           Treat all warnings as errors, which are reflected as command exit status.

       -b blocksize
           Use defined block size, which has to be divisible by page size.

       -e edition
           Use defined file system edition number in superblock.

       -N big, little, host
           Use defined endianness. Value defaults to host.

       -i file
           Insert a file to cramfs file system.

       -n name
           Set name of the cramfs file system.

       -p
           Pad by 512 bytes for boot code.

       -s
           This option is ignored. Originally the -s turned on directory entry sorting.

       -z
           Make explicit holes.

       -l[=mode]
           Use exclusive BSD lock for device or file it operates. The optional argument mode can
           be yes, no (or 1 and 0) or nonblock. If the mode argument is omitted, it defaults to
           "yes". This option overwrites environment variable $LOCK_BLOCK_DEVICE. The default is
           not to use any lock at all, but it’s recommended to avoid collisions with udevd or
           other tools.

       -h, --help
           Display help text and exit.

       -V, --version
           Print version and exit.

EXIT STATUS

       0
           success

       8
           operation error, such as unable to allocate memory

SEE ALSO

       fsck.cramfs(8), mount(8)

REPORTING BUGS

       For bug reports, use the issue tracker at https://github.com/util-linux/util-linux/issues.

AVAILABILITY

       The mkfs.cramfs command is part of the util-linux package which can be downloaded from
       Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.