MKFS.CRAMFS(8) System Administration MKFS.CRAMFS(8)
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 ex-
pressed in a terse representation that is more space-efficient than
conventional file systems.
The file system is intentionally read-only to simplify its design; ran-
dom write access for compressed files is difficult to implement.
cramfs ships with a utility (mkcramfs) 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 re-
turn value.
-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.
-h, --help
Display help text and exit.
-V, --version
Display version information and exit.
EXIT STATUS
0 success
8 operation error, such as unable to allocate memory
SEE ALSO
fsck.cramfs(8), mount(8)
AVAILABILITY
The example command is part of the util-linux package and is available
from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-
linux/>.
util-linux April 2013 MKFS.CRAMFS(8)