NAME

       tar2sqfs - create a SquashFS image from a tar archive

SYNOPSIS

       tar2sqfs [OPTIONS...] <sqfsfile>

DESCRIPTION

       Quickly and painlessly turn a tar ball into a SquashFS filesystem image.

       By  default,  the  program  reads the archive from standard input. Compressed archives are
       supported.

       Possible options:

       --root-becomes, -r <dir>
              If set, only pack entries that are underneath the specified directory.  The  prefix
              is  stripped and the meta data for the directory itself is copied to the root inode
              (i.e. the ownership, permissions, extended attributes, modification time).

              If this option is not set, tar2sqfs implicitly treats ./  or  absolute  paths  this
              way, i.e. if the archive contains an entry for ./, it becomes the root node and the
              prefix is stripped from all paths (and similar for absolute paths and /).

       --no-symlink-retarget, -S
              If --root-becomes is used, link targets are adjusted if they are  prefixed  by  the
              root path. By default, this is also done on symbolic links, that have a target that
              is prefixed by the root path and they are converted  to  aboluste  paths  with  the
              prefix  removed.  However, because symlinks can point across mount points, this may
              actually be intended for some use cases.

              This flag allows changing the default behaviour, so only hard links are retargeted.

       --exclude, -E <pattern>
              Test paths against a given shell-style globbing pattern and  exclude  all  matches,
              e.g.  --exclude  boot/* keeps the boot directory in the final SquashFS archive, but
              drops all of its contents.

       --compressor, -c <name>
              Select the compressor to use.  Run tar2sqfs --help to get a list of  all  available
              compressors and the default selection.

       --comp-extra, -X <options>
              A  comma  separated list of extra options for the selected compressor. Specify help
              to get a list of available options.

       --num-jobs, -j <count>
              If libsquashfs was compiled with a thread pool  based,  parallel  data  compressor,
              this  option  can  be used to set the number of compressor threads. If not set, the
              default is the number of available CPU cores.

       --queue-backlog, -Q <count>
              Maximum number of data blocks in the thread worker queue before the  packer  starts
              waiting for the block processors to catch up. Higher values result in higher memory
              consumption. Defaults to 10 times the number of workers.

       --block-size, -b <size>
              Block size to use for SquashFS image.  Defaults to 131072.

       --dev-block-size, -B <size>
              Device block size to padd the image to.  Defaults to 4096.

       --defaults, -d <options>
              A comma separated list of default values for implicitly created  directories.   The
              following values can be set:

              ┌──────────────┬────────────────────────────────────────┐
              │Option        │ Default                                │
              ├──────────────┼────────────────────────────────────────┤
              │uid=<value>   │ 0                                      │
              ├──────────────┼────────────────────────────────────────┤
              │gid=<value>   │ 0                                      │
              ├──────────────┼────────────────────────────────────────┤
              │mode=<value>  │ 0755                                   │
              ├──────────────┼────────────────────────────────────────┤
              │mtime=<value> │ $SOURCE_DATE_EPOCH if set, 0 otherwise │
              └──────────────┴────────────────────────────────────────┘

       --no-keep-time, -k
              Replace  the  time  stamps  from  the  tar archive with default time stamps for all
              entries.

              The default behavior is to preserve the time stamps from the archive to the  extent
              possible  (SquashFS  has  second  resolution  and  32  bit time stamps; tar can use
              extensions to specify much larger timestamps with arbitrary  precision).  The  root
              inode  (unless  --root-becomes  is  used) and the modification time on the SquashFS
              image itself will still be set to defaults.

       --no-xattr, -x
              Do not copy extended attributes from archive. Default  behaviour  is  to  copy  all
              extended attributes and skip the ones that cannot be encoded in SquashFS.

       --no-skip, -s
              Abort if a tar record cannot be read instead of skipping it.

       --exportable, -e
              Generate an export table for NFS support.

       --no-tail-packing, -T
              Do  not  perform tail end packing on files that are larger than the specified block
              size.

       --no-pad
              Do not pad the resulting image to device block size. May result in  an  image  that
              cannot be loop mounted.

       --force, -f
              Overwrite the output file if it exists.

       --quiet, -q
              Do not print out progress reports.

       --help, -h
              Print help text and exit.

       --version, -V
              Print version information and exit.

COMPATIBILITY

       Currently  the  program  can  process  v7  format,  pre-POSIX ustar, POSIX tar and GNU tar
       archives. PAX extension headers are also supported. Global PAX headers are ignored.

       The support for GNU tar is limited to a commonly used subset (i.e. some legacy  extensions
       that  GNU  tar  itself  no  longer  generates  are not supported; neither are multi volume
       archives).

       The input tar file can either be uncompressed, or stream compressed using gzip,  xz,  zstd
       or  bzip2.  The  program  transparently  auto-detects  and  unpacks  any stream compressed
       archive. The exact list of supported compressors depends on the compile configuration.

       Extended attributes are supported through the SCHILY.xattr extension (favoured by GNU  tar
       and star) or through the LIBARCHIVE.xattr extension.

       If  any  unsupported  section  or  extended  attribute key is encountered in an archive, a
       warning message is written to stderr. If the --no-skip option is set,  processing  aborts.
       By  default, unknown sections and unsupported extended attributes are simply skipped after
       issuing a warning.

ENVIRONMENT

       If the command line switch --defaults is not used or no default mtime  is  specified,  the
       value  of  the  environment variable SOURCE_DATE_EPOCH is used for all file and filesystem
       timestamps.

       If SOURCE_DATE_EPOCH is not set, not a  parsable  number  or  it  is  out  of  range,  the
       timestamps default to 0.

       Environment variables are only used if no explicit command line switches are set. Explicit
       command line switches are always preferred over the environment variables.

EXAMPLES

       Turn an uncompressed tar archive into a SquashFS image:

              tar2sqfs rootfs.sqfs < rootfs.tar.gz

SEE ALSO

       gensquashfs(1), rdsquashfs(1), sqfs2tar(1)

AUTHOR

       Written by David Oberhollenzer.

COPYRIGHT

       Copyright ©  2019  David  Oberhollenzer  License  GPLv3+:  GNU  GPL  version  3  or  later
       <https://gnu.org/licenses/gpl.html>.
       This  is free software: you are free to change and redistribute it.  There is NO WARRANTY,
       to the extent permitted by law.