'\" t
.\"     Title: mkfs.cramfs
.\"    Author: [see the "AUTHOR(S)" section]
.\" Generator: Asciidoctor 2.0.15
.\"      Date: 2022-02-17
.\"    Manual: System Administration
.\"    Source: util-linux 2.38
.\"  Language: English
.\"
.TH "MKFS.CRAMFS" "8" "2022-02-17" "util\-linux 2.38" "System Administration"
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.SH "NAME"
mkfs.cramfs \- make compressed ROM file system
.SH "SYNOPSIS"
.sp
\fBmkfs.cramfs\fP [options] \fIdirectory file\fP
.SH "DESCRIPTION"
.sp
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.
.sp
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 (\fBmkcramfs\fP(8)) to pack files into new cramfs images.
.sp
File sizes are limited to less than 16 MB.
.sp
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.)
.SH "ARGUMENTS"
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The \fIdirectory\fP is simply the root of the directory tree that we want to generate a compressed filesystem out of.
.sp
The \fIfile\fP will contain the cram file system, which later can be mounted.
.SH "OPTIONS"
.sp
\fB\-v\fP
.RS 4
Enable verbose messaging.
.RE
.sp
\fB\-E\fP
.RS 4
Treat all warnings as errors, which are reflected as command exit status.
.RE
.sp
\fB\-b\fP \fIblocksize\fP
.RS 4
Use defined block size, which has to be divisible by page size.
.RE
.sp
\fB\-e\fP \fIedition\fP
.RS 4
Use defined file system edition number in superblock.
.RE
.sp
\fB\-N\fP \fIbig, little, host\fP
.RS 4
Use defined endianness. Value defaults to \fIhost\fP.
.RE
.sp
\fB\-i\fP \fIfile\fP
.RS 4
Insert a \fIfile\fP to cramfs file system.
.RE
.sp
\fB\-n\fP \fIname\fP
.RS 4
Set name of the cramfs file system.
.RE
.sp
\fB\-p\fP
.RS 4
Pad by 512 bytes for boot code.
.RE
.sp
\fB\-s\fP
.RS 4
This option is ignored. Originally the \fB\-s\fP turned on directory entry sorting.
.RE
.sp
\fB\-z\fP
.RS 4
Make explicit holes.
.RE
.sp
\fB\-h\fP, \fB\-\-help\fP
.RS 4
Display help text and exit.
.RE
.sp
\fB\-V\fP, \fB\-\-version\fP
.RS 4
Print version and exit.
.RE
.SH "EXIT STATUS"
.sp
\fB0\fP
.RS 4
success
.RE
.sp
\fB8\fP
.RS 4
operation error, such as unable to allocate memory
.RE
.SH "SEE ALSO"
.sp
\fBfsck.cramfs\fP(8),
\fBmount\fP(8)
.SH "REPORTING BUGS"
.sp
For bug reports, use the issue tracker at \c
.URL "https://github.com/util\-linux/util\-linux/issues" "" "."
.SH "AVAILABILITY"
.sp
The \fBmkfs.cramfs\fP command is part of the util\-linux package which can be downloaded from \c
.URL "https://www.kernel.org/pub/linux/utils/util\-linux/" "Linux Kernel Archive" "."