1TAR2SQFS(1) User Commands TAR2SQFS(1)
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6 tar2sqfs - create a SquashFS image from a tar archive
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9 tar2sqfs [OPTIONS...] <sqfsfile>
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12 Quickly and painlessly turn a tar ball into a SquashFS filesystem im‐
13 age.
14 By default, the program reads the archive from standard input. Com‐
16 pressed archives are supported.
17 Possible options:
19 --root-becomes, -r <dir>
21 If set, only pack entries that are underneath the specified di‐
22 rectory. The prefix is stripped and the meta data for the direc‐
23 tory itself is copied to the root inode (i.e. the ownership,
24 permissions, extended attributes, modification time).
25 If this option is not set, tar2sqfs implicitly treats ./ or ab‐
27 solute paths this way, i.e. if the archive contains an entry for
28 ./, it becomes the root node and the prefix is stripped from all
29 paths (and similar for absolute paths and /).
30 --no-symlink-retarget, -S
32 If --root-becomes is used, link targets are adjusted if they are
33 prefixed by the root path. By default, this is also done on sym‐
34 bolic links, that have a target that is prefixed by the root
35 path and they are converted to aboluste paths with the prefix
36 removed. However, because symlinks can point across mount
37 points, this may actually be intended for some use cases.
38 This flag allows changing the default behaviour, so only hard
40 links are retargeted.
41 --compressor, -c <name>
43 Select the compressor to use. Run tar2sqfs --help to get a list
44 of all available compressors and the default selection.
45 --comp-extra, -X <options>
47 A comma separated list of extra options for the selected com‐
48 pressor. Specify help to get a list of available options.
49 --num-jobs, -j <count>
51 If libsquashfs was compiled with a thread pool based, parallel
52 data compressor, this option can be used to set the number of
53 compressor threads. If not set, the default is the number of
54 available CPU cores.
55 --queue-backlog, -Q <count>
57 Maximum number of data blocks in the thread worker queue before
58 the packer starts waiting for the block processors to catch up.
59 Higher values result in higher memory consumption. Defaults to
60 10 times the number of workers.
61 --block-size, -b <size>
63 Block size to use for SquashFS image. Defaults to 131072.
64 --dev-block-size, -B <size>
66 Device block size to padd the image to. Defaults to 4096.
67 --defaults, -d <options>
69 A comma separated list of default values for implicitly created
70 directories. The following values can be set:
71 ┌──────────────┬────────────────────────────────────────┐
73 │Option │ Default │
74 ├──────────────┼────────────────────────────────────────┤
75 │uid=<value> │ 0 │
76 ├──────────────┼────────────────────────────────────────┤
77 │gid=<value> │ 0 │
78 ├──────────────┼────────────────────────────────────────┤
79 │mode=<value> │ 0755 │
80 ├──────────────┼────────────────────────────────────────┤
81 │mtime=<value> │ $SOURCE_DATE_EPOCH if set, 0 otherwise │
82 └──────────────┴────────────────────────────────────────┘
83 --no-keep-time, -k
85 Replace the time stamps from the tar archive with default time
86 stamps for all entries.
87 The default behavior is to preserve the time stamps from the ar‐
89 chive to the extent possible (SquashFS has second resolution and
90 32 bit time stamps; tar can use extensions to specify much
91 larger timestamps with arbitrary precision). The root inode (un‐
92 less --root-becomes is used) and the modification time on the
93 SquashFS image itself will still be set to defaults.
94 --no-xattr, -x
96 Do not copy extended attributes from archive. Default behaviour
97 is to copy all extended attributes and skip the ones that cannot
98 be encoded in SquashFS.
99 --no-skip, -s
101 Abort if a tar record cannot be read instead of skipping it.
102 --exportable, -e
104 Generate an export table for NFS support.
105 --no-tail-packing, -T
107 Do not perform tail end packing on files that are larger than
108 the specified block size.
109 --force, -f
111 Overwrite the output file if it exists.
112 --quiet, -q
114 Do not print out progress reports.
115 --help, -h
117 Print help text and exit.
118 --version, -V
120 Print version information and exit.
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123 Currently the program can process v7 format, pre-POSIX ustar, POSIX tar
124 and GNU tar archives. PAX extension headers are also supported. Global
125 PAX headers are ignored.
126 The support for GNU tar is limited to a commonly used subset (i.e. some
128 legacy extensions that GNU tar itself no longer generates are not sup‐
129 ported; neither are multi volume archives).
130 The input tar file can either be uncompressed, or stream compressed us‐
132 ing gzip, xz, zstd or bzip2. The program transparently auto-detects and
133 unpacks any stream compressed archive. The exact list of supported com‐
134 pressors depends on the compile configuration.
135 Extended attributes are supported through the SCHILY.xattr extension
137 (favoured by GNU tar and star) or through the LIBARCHIVE.xattr exten‐
138 sion.
139 If any unsupported section or extended attribute key is encountered in
141 an archive, a warning message is written to stderr. If the --no-skip
142 option is set, processing aborts. By default, unknown sections and un‐
143 supported extended attributes are simply skipped after issuing a warn‐
144 ing.
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147 If the command line switch --defaults is not used or no default mtime
148 is specified, the value of the environment variable SOURCE_DATE_EPOCH
149 is used for all file and filesystem timestamps.
150 If SOURCE_DATE_EPOCH is not set, not a parsable number or it is out of
152 range, the timestamps default to 0.
153 Environment variables are only used if no explicit command line
155 switches are set. Explicit command line switches are always preferred
156 over the environment variables.
157
159 Turn an uncompressed tar archive into a SquashFS image:
160 tar2sqfs rootfs.sqfs < rootfs.tar.gz
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164 gensquashfs(1), rdsquashfs(1), sqfs2tar(1)
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167 Written by David Oberhollenzer.
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170 Copyright © 2019 David Oberhollenzer License GPLv3+: GNU GPL version 3
171 or later <https://gnu.org/licenses/gpl.html>.
172 This is free software: you are free to change and redistribute it.
173 There is NO WARRANTY, to the extent permitted by law.
174tar2sqfs June 2019 TAR2SQFS(1)