MKFS.CRAMFS(8) System Administration MKFS.CRAMFS(8)
mkfs.cramfs - make compressed ROM file system
mkfs.cramfs [options] directory file
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) 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.)
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.
-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. -h, --help Display help text and exit. -V, --version Display version information and exit.
0 success 8 operation error, such as unable to allocate memory
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/⟩.
This page is part of the util-linux (a random collection of Linux utilities) project. Information about the project can be found at ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have a bug report for this manual page, send it to firstname.lastname@example.org. This page was obtained from the project's upstream Git repository ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on 2020-05-27. (At that time, the date of the most recent commit that was found in the repository was 2020-05-27.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to email@example.com util-linux April 2013 MKFS.CRAMFS(8)
Pages that refer to this page: fsck.cramfs(8), systemd-makefs@.service(8)