disk-utils/mkfs.cramfs.8.adoc

   1 //po4a: entry man manual
   2 = mkfs.cramfs(8)
   3 :doctype: manpage
   4 :man manual: System Administration
   5 :man source: util-linux {release-version}
   6 :page-layout: base
   7 :command: mkfs.cramfs
   8
   9 == NAME
  10
  11 mkfs.cramfs - make compressed ROM file system
  12
  13 == SYNOPSIS
  14
  15 *mkfs.cramfs* [options] _directory file_
  16
  17 == DESCRIPTION
  18
  19 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.
  20
  21 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.
  22
  23 File sizes are limited to less than 16 MB.
  24
  25 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.)
  26
  27 == ARGUMENTS
  28
  29 The _directory_ is simply the root of the directory tree that we want to generate a compressed filesystem out of.
  30
  31 The _file_ will contain the cram file system, which later can be mounted.
  32
  33 == OPTIONS
  34
  35 *-v*::
  36 Enable verbose messaging.
  37
  38 *-E*::
  39 Treat all warnings as errors, which are reflected as command exit status.
  40
  41 *-b* _blocksize_::
  42 Use defined block size, which has to be divisible by page size.
  43
  44 *-e* _edition_::
  45 Use defined file system edition number in superblock.
  46
  47 *-N* _big, little, host_::
  48 Use defined endianness. Value defaults to _host_.
  49
  50 *-i* _file_::
  51 Insert a _file_ to cramfs file system.
  52
  53 *-n* _name_::
  54 Set name of the cramfs file system.
  55
  56 *-p*::
  57 Pad by 512 bytes for boot code.
  58
  59 *-s*::
  60 This option is ignored. Originally the *-s* turned on directory entry sorting.
  61
  62 *-z*::
  63 Make explicit holes.
  64
  65 *-l*\fR[=\fImode\fR]::
  66  Use exclusive BSD lock for device or file it operates.  The optional argument
  67  \fImode\fP can be \fByes\fR, \fBno\fR (or 1 and 0) or \fBnonblock\fR.  If the \fImode\fR
  68  argument is omitted, it defaults to \fB"yes"\fR.  This option overwrites
  69  environment variable \fB$LOCK_BLOCK_DEVICE\fR.  The default is not to use any
  70  lock at all, but it's recommended to avoid collisions with udevd or other
  71  tools.
  72  .TP
  73
  74 include::man-common/help-version.adoc[]
  75
  76 == EXIT STATUS
  77
  78 *0*::
  79 success
  80 *8*::
  81 operation error, such as unable to allocate memory
  82
  83 == SEE ALSO
  84
  85 *fsck.cramfs*(8),
  86 *mount*(8)
  87
  88 include::man-common/bugreports.adoc[]
  89
  90 include::man-common/footer.adoc[]
  91
  92 ifdef::translation[]
  93 include::man-common/translation.adoc[]
  94 endif::[]