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//po4a: entry man manual
= mkfs.cramfs(8)
:doctype: manpage
:man manual: System Administration
:man source: util-linux {release-version}
:page-layout: base
:command: mkfs.cramfs
== 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.
include::man-common/help-version.adoc[]
== EXIT STATUS
*0*::
success
*8*::
operation error, such as unable to allocate memory
== SEE ALSO
*fsck.cramfs*(8),
*mount*(8)
include::man-common/bugreports.adoc[]
include::man-common/footer.adoc[]
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include::man-common/translation.adoc[]
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