(tar.info.gz) Attributes

 
 8.2 Handling File Attributes
 ============================
 
 When `tar' reads files, it updates their access times.  To avoid this,
 use the `--atime-preserve[=METHOD]' option, which can either reset the
 access time retroactively or avoid changing it in the first place.
 
 `--atime-preserve'
 `--atime-preserve=replace'
 `--atime-preserve=system'
      Preserve the access times of files that are read.  This works only
      for files that you own, unless you have superuser privileges.
 
      `--atime-preserve=replace' works on most systems, but it also
      restores the data modification time and updates the status change
      time.  Hence it doesn't interact with incremental dumps nicely
      ( Incremental Dumps), and it can set access or data
      modification times incorrectly if other programs access the file
      while `tar' is running.
 
      `--atime-preserve=system' avoids changing the access time in the
      first place, if the operating system supports this.
      Unfortunately, this may or may not work on any given operating
      system or file system.  If `tar' knows for sure it won't work, it
      complains right away.
 
      Currently `--atime-preserve' with no operand defaults to
      `--atime-preserve=replace', but this is intended to change to
      `--atime-preserve=system' when the latter is better-supported.
 
 `-m'
 `--touch'
      Do not extract data modification time.
 
      When this option is used, `tar' leaves the data modification times
      of the files it extracts as the times when the files were
      extracted, instead of setting it to the times recorded in the
      archive.
 
      This option is meaningless with `--list' (`-t').
 
 `--same-owner'
      Create extracted files with the same ownership they have in the
      archive.
 
      This is the default behavior for the superuser, so this option is
      meaningful only for non-root users, when `tar' is executed on
      those systems able to give files away.  This is considered as a
      security flaw by many people, at least because it makes quite
      difficult to correctly account users for the disk space they
      occupy.  Also, the `suid' or `sgid' attributes of files are easily
      and silently lost when files are given away.
 
      When writing an archive, `tar' writes the user ID and user name
      separately.  If it can't find a user name (because the user ID is
      not in `/etc/passwd'), then it does not write one.  When restoring,
      it tries to look the name (if one was written) up in
      `/etc/passwd'.  If it fails, then it uses the user ID stored in
      the archive instead.
 
 `--no-same-owner'
 `-o'
      Do not attempt to restore ownership when extracting.  This is the
      default behavior for ordinary users, so this option has an effect
      only for the superuser.
 
 `--numeric-owner'
      The `--numeric-owner' option allows (ANSI) archives to be written
      without user/group name information or such information to be
      ignored when extracting.  It effectively disables the generation
      and/or use of user/group name information.  This option forces
      extraction using the numeric ids from the archive, ignoring the
      names.
 
      This is useful in certain circumstances, when restoring a backup
      from an emergency floppy with different passwd/group files for
      example.  It is otherwise impossible to extract files with the
      right ownerships if the password file in use during the extraction
      does not match the one belonging to the file system(s) being
      extracted.  This occurs, for example, if you are restoring your
      files after a major crash and had booted from an emergency floppy
      with no password file or put your disk into another machine to do
      the restore.
 
      The numeric ids are _always_ saved into `tar' archives.  The
      identifying names are added at create time when provided by the
      system, unless `--format=oldgnu' is used.  Numeric ids could be
      used when moving archives between a collection of machines using a
      centralized management for attribution of numeric ids to users and
      groups.  This is often made through using the NIS capabilities.
 
      When making a `tar' file for distribution to other sites, it is
      sometimes cleaner to use a single owner for all files in the
      distribution, and nicer to specify the write permission bits of the
      files as stored in the archive independently of their actual value
      on the file system.  The way to prepare a clean distribution is
      usually to have some Makefile rule creating a directory, copying
      all needed files in that directory, then setting ownership and
      permissions as wanted (there are a lot of possible schemes), and
      only then making a `tar' archive out of this directory, before
      cleaning everything out.  Of course, we could add a lot of options
      to GNU `tar' for fine tuning permissions and ownership.  This is
      not the good way, I think.  GNU `tar' is already crowded with
      options and moreover, the approach just explained gives you a
      great deal of control already.
 
 `-p'
 `--same-permissions'
 `--preserve-permissions'
      Extract all protection information.
 
      This option causes `tar' to set the modes (access permissions) of
      extracted files exactly as recorded in the archive.  If this option
      is not used, the current `umask' setting limits the permissions on
      extracted files.  This option is by default enabled when `tar' is
      executed by a superuser.
 
      This option is meaningless with `--list' (`-t').
 
 `--preserve'
      Same as both `--same-permissions' and `--same-order'.
 
      This option is deprecated, and will be removed in GNU `tar'
      version 1.23.
 
 `--acls'
      This option causes `tar' to store the current ACL in the archive.
 
      The `--acls' option has no equivalent short option name.
 
 `--selinux'
      This option causes `tar' to store the current SELinux security
      context information in the archive.
 
      The `--selinux' option has no equivalent short option name.
 
 `--xattrs'
      This option causes `tar' to store the current extended attributes
      in the archive. This option also enables `--acls' and `--selinux'
      if they haven't been set already.
 
      The `--xattrs' option has no equivalent short option name.
 
 `--no-acls'
      This option causes `tar' not to store the current ACL in the
      archive and not to extract any ACL information in an archive.
 
      The `--no-acls' option has no equivalent short option name.
 
 `--no-selinux'
      This option causes `tar' not to store the current SELinux security
      context information in the archive and not to extract any SELinux
      information in an archive.
 
      The `--no-selinux' option has no equivalent short option name.
 
 `--no-xattrs'
      This option causes `tar' not to store the current extended
      attributes in the archive and not to extract any extended
      attributes in an archive. This option also enables `--no-acls' and
      `--no-selinux' if they haven't been set already.
 
      The `--no-xattrs' option has no equivalent short option name.
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