# man > MKFS.CRAMFS(8)

[_MKFS.CRAMFS_(8)](https://www.chedong.com/phpMan.php/man/MKFS.CRAMFS/8/markdown)                          System Administration                         [_MKFS.CRAMFS_(8)](https://www.chedong.com/phpMan.php/man/MKFS.CRAMFS/8/markdown)

## 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)](https://www.chedong.com/phpMan.php/man/mkcramfs/8/markdown)) 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 _
           Use defined block size, which has to be divisible by page size.

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

### -N _
           Use defined endianness. Value defaults to _host_.

### -i _
           Insert a _file_ to cramfs file system.

### -n _
           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
           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)](https://www.chedong.com/phpMan.php/man/fsck.cramfs/8/markdown), [**mount**(8)](https://www.chedong.com/phpMan.php/man/mount/8/markdown)

## 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/>>.

util-linux 2.39.3                            2023-11-21                               [_MKFS.CRAMFS_(8)](https://www.chedong.com/phpMan.php/man/MKFS.CRAMFS/8/markdown)