mkfs.cramfs(8)

1MKFS.CRAMFS(8)               System Administration              MKFS.CRAMFS(8)
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NAME

6       mkfs.cramfs - make compressed ROM file system
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SYNOPSIS

9       mkfs.cramfs [options] directory file
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DESCRIPTION

12       Files  on cramfs file systems are zlib-compressed one page at a time to
13       allow random read access.  The  metadata  is  not  compressed,  but  is
14       expressed  in  a terse representation that is more space-efficient than
15       conventional file systems.
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17       The file system is intentionally read-only to simplify its design; ran‐
18       dom  write  access  for  compressed  files  is  difficult to implement.
19       cramfs ships with a utility (mkcramfs) to pack files  into  new  cramfs
20       images.
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22       File sizes are limited to less than 16 MB.
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24       Maximum  file  system size is a little under 272 MB.  (The last file on
25       the file system must begin before the 256 MB block, but can extend past
26       it.)
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ARGUMENTS

29       The  directory is simply the root of the directory tree that we want to
30       generate a compressed filesystem out of.
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32       The file will contain the cram file system, which later can be mounted.
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OPTIONS

35       -v     Enable verbose messaging.
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37       -E     Treat all warnings as errors, which  are  reflected  as  command
38              exit status.
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40       -b blocksize
41              Use defined block size, which has to be divisible by page size.
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43       -e edition
44              Use defined file system edition number in superblock.
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46       -N big, little, host
47              Use defined endianness.  Value defaults to host.
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49       -i file
50              Insert a file to cramfs file system.
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52       -n name
53              Set name of the cramfs file system.
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55       -p     Pad by 512 bytes for boot code.
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57       -s     This  option  is ignored.  Originally the -s turned on directory
58              entry sorting.
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60       -z     Make explicit holes.
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62       -h, --help
63              Display help text and exit.
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65       -V, --version
66              Display version information and exit.
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EXIT STATUS

69              0      success
70              8      operation error, such as unable to allocate memory
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AVAILABILITY

76       The mkfs.cramfs command is part of the util-linux package and is avail‐
77       able  from Linux Kernel Archive ⟨https://www.kernel.org/pub/linux/utils
78       /util-linux/⟩.
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82util-linux                        April 2013                    MKFS.CRAMFS(8)