SQFSTAR(1) User Commands SQFSTAR(1)
NAME
sqfstar - tool to create a squashfs filesystem from a tar archive
SYNOPSIS
cat xxx.tar | sqfstar [OPTIONS] FILESYSTEM [exclude files]
zcat xxx.tgz | sqfstar [OPTIONS] FILESYSTEM [exclude files]
xzcat xxx.tar.xz | sqfstar [OPTIONS] FILESYSTEM [exclude files]
zstdcat xxx.tar.zst | sqfstar [OPTIONS] FILESYSTEM [exclude files]
DESCRIPTION
Squashfs is a highly compressed read-only filesystem for Linux. It
uses either gzip/xz/lzo/lz4/zstd compression to compress both files,
inodes and directories. Inodes in the system are very small and all
blocks are packed to minimise data overhead. Block sizes greater than
4K are supported up to a maximum of 1Mbytes (default block size 128K).
Squashfs is intended for general read-only filesystem use, for archival
use (i.e. in cases where a .tar.gz file may be used), and in con-
strained block device/memory systems (e.g. embedded systems) where low
overhead is needed.
OPTIONS
Filesystem build options:
-comp COMP
select COMP compression. Compressors available: gzip (default),
lzo, lz4, xz, zstd, lzma.
-b BLOCK_SIZE
set data block to BLOCK_SIZE. Default 128 Kbytes. Optionally a
suffix of K or M can be given to specify Kbytes or Mbytes re-
spectively.
-reproducible
build filesystems that are reproducible (default).
-not-reproducible
build filesystems that are not reproducible.
-mkfs-time TIME
set filesystem creation timestamp to TIME, which is an unsigned
32-bit int indicating seconds since the epoch (1970-01-01).
-fstime TIME
synonym for mkfs-time.
-all-time TIME
set all file timestamps to TIME, which is an unsigned 32-bit int
indicating seconds since the epoch (1970-01-01).
-exports
make the filesystem exportable via NFS.
-no-sparse
don't detect sparse files.
-no-xattrs
don't store extended attributes.
-xattrs
store extended attributes (default).
-noI do not compress inode table.
-noId do not compress the uid/gid table (implied by -noI).
-noD do not compress data blocks.
-noF do not compress fragment blocks.
-noX do not compress extended attributes.
-no-fragments
do not use fragments.
-no-tailends
don't pack tail ends into fragments.
-no-duplicates
do not perform duplicate checking.
-no-hardlinks
do not hardlink files, instead store duplicates.
-all-root
make all files owned by root.
-root-time TIME
set root directory time to TIME.
-root-mode MODE
set root directory permissions to octal MODE.
-root-uid UID
set root directory owner to UID.
-root-gid GID
set root directory group to GID.
-force-uid UID
set all file uids to UID.
-force-gid GID
set all file gids to GID.
Filesystem filter options:
-ef EXCLUDE_FILE
list of exclude dirs/files. One per line.
-regex Allow POSIX regular expressions to be used in exclude
dirs/files.
Sqfstar runtime options:
-version
print version, licence and copyright message.
-force force Sqfstar to write to block device or file.
-exit-on-error
treat normally ignored errors as fatal.
-quiet no verbose output.
-info print files written to filesystem.
-no-progress
don't display the progress bar.
-progress
display progress bar when using the -info option.
-throttle PERCENTAGE
throttle the I/O input rate by the given percentage. This can be
used to reduce the I/O and CPU consumption of Mksquashfs.
-limit PERCENTAGE
limit the I/O input rate to the given percentage. This can be
used to reduce the I/O and CPU consumption of Mksquashfs (alter-
native to -throttle).
-processors NUMBER
Use NUMBER processors. By default will use number of processors
available.
-mem SIZE
Use SIZE physical memory. Optionally a suffix of K, M or G can
be given to specify Kbytes, Mbytes or Gbytes respectively.
Expert options (these may make the filesystem unmountable):
-nopad do not pad filesystem to a multiple of 4K.
-offset OFFSET
Skip OFFSET bytes at the beginning of FILESYSTEM. Optionally a
suffix of K, M or G can be given to specify Kbytes, Mbytes or
Gbytes respectively. Default 0 bytes.
-o OFFSET
synonym for -offset.
Miscellaneous options:
-root-owned
alternative name for -all-root.
-noInodeCompression
alternative name for -noI.
-noIdTableCompression
alternative name for -noId.
-noDataCompression
alternative name for -noD.
-noFragmentCompression
alternative name for -noF.
-noXattrCompression
alternative name for -noX.
-help output this options text to stdout.
-h output this options text to stdout.
-Xhelp print compressor options for selected compressor.
COMPRESSORS AVAILABLE AND COMPRESSOR SPECIFIC OPTIONS
gzip (default):
-Xcompression-level COMPRESSION-LEVEL
COMPRESSION-LEVEL should be 1 .. 9 (default 9).
-Xwindow-size WINDOW-SIZE
WINDOW-SIZE should be 8 .. 15 (default 15).
-Xstrategy strategy1,strategy2,...,strategyN
Compress using strategy1,strategy2,...,strategyN in turn and
choose the best compression. Available strategies: default, fil-
tered, huffman_only, run_length_encoded and fixed.
lzo:
-Xalgorithm ALGORITHM
Where ALGORITHM is one of: lzo1x_1, lzo1x_1_11, lzo1x_1_12,
lzo1x_1_15, lzo1x_999 (default).
-Xcompression-level COMPRESSION-LEVEL
COMPRESSION-LEVEL should be 1 .. 9 (default 8) Only applies to
lzo1x_999 algorithm.
lz4:
-Xhc Compress using LZ4 High Compression.
xz:
-Xbcj filter1,filter2,...,filterN
Compress using filter1,filter2,...,filterN in turn (in addition
to no filter), and choose the best compression. Available fil-
ters: x86, arm, armthumb, powerpc, sparc, ia64.
-Xdict-size DICT-SIZE
Use DICT-SIZE as the XZ dictionary size. The dictionary size
can be specified as a percentage of the block size, or as an ab-
solute value. The dictionary size must be less than or equal to
the block size and 8192 bytes or larger. It must also be
storable in the xz header as either 2^n or as 2^n+2^(n+1). Exam-
ple dict-sizes are 75%, 50%, 37.5%, 25%, or 32K, 16K, 8K etc.
zstd:
-Xcompression-level COMPRESSION-LEVEL
COMPRESSION-LEVEL should be 1 .. 22 (default 15).
lzma:
(no options) (deprecated - no kernel support)
ENVIRONMENT
SOURCE_DATE_EPOCH
If set, this is used as the filesystem creation timestamp. Also
any file timestamps which are after SOURCE_DATE_EPOCH will be
clamped to SOURCE_DATE_EPOCH. See https://repro-
ducible-builds.org/docs/source-date-epoch/ for more information.
EXAMPLES
sqfstar IMAGE.SQFS < archive.tar
Create a Squashfs filesystem from the uncompressed tar file "ar-
chive.tar". Sqfstar will use the default compressor (normally
gzip), and block size of 128 Kbytes.
zcat archive.tgz | sqfstar IMAGE.SQFS
Create a Squashfs filesystem from the compressed tar file "ar-
chive.tgz". Sqfstar will use the default compressor (normally
gzip), and block size of 128 Kbytes.
sqfstar -b 1M -comp zstd IMAGE.SQFS < archive.tar
Use a block size of 1 Mbyte and Zstandard compression to create
the filesystem.
sqfstar -root-uid 0 -root-gid 0 IMAGE.SQFS < archive.tar
Tar files do not supply a definition for the root directory, and
the default is to make the directory owned/group owned by the
user running Sqfstar. The above command sets the owner-
ship/group ownership to root.
sqfstar -root-mode 0755 IMAGE.SQFS < archive.tar
The default permissions for the root directory is 0777 (rwxr-
wxrwx). The above command sets the permissions to 0755 (rwxr-
xr-x).
sqfstar IMAGE.SQFS file1 file2 < archive.tar
Exclude file1 and file2 from the tar file when creating filesys-
tem.
sqfstar IMAGE.SQFS "*.gz" < archive.tar
Exclude any files in the top level directory which matches the
wildcard pattern "*.gz".
sqfstar IMAGE.SQFS "... *.gz" < archive.tar
Exclude any file which matches the wildcard pattern "*.gz" any-
where within the tar file. The initial "..." indicates the
wildcard pattern is "non-anchored" and will match anywhere.
Note: when passing wildcarded names to Sqfstar, they should be quoted
(as in the above examples), to ensure that they are not processed by
the shell.
AUTHOR
Written by Phillip Lougher <phillip@squashfs.org.uk>
COPYRIGHT
Copyright © 2022 Phillip Lougher <phillip@squashfs.org.uk>
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MER-
CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
Public License for more details.
SEE ALSO
mksquashfs(1), unsquashfs(1), sqfscat(1)
The README for the Squash-tools 4.5.1 release, describing the new fea-
tures can be read here
https://github.com/plougher/squashfs-tools/blob/master/README-4.5.1
The Squashfs-tools USAGE guide can be read here
https://github.com/plougher/squashfs-tools/blob/master/USAGE
sqfstar version 4.5.1 March 2022 SQFSTAR(1)
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