STAR(4L)						      Schily's USER COMMANDS							  STAR(4L)

NAME

       star - tape archive file format

DESCRIPTION

       Tar  Archives  are  layered  archives.	The  basic structure is defined by the POSIX.1-1988 archive format and documented in the BASIC TAR
       HEADER DESCRIPTION section below.  The higher level structure is defined by  the  POSIX.1-2001  extended  headers  and  documented  in  the
       EXTENDED  TAR  (PAX)  HEADER  STRUCTURE	section below.	POSIX.1-2001 extended headers are pseudo files that contain an unlimited number of
       extended header keywords and associated values. The header keywords are documented in the EXTENDED TAR (PAX) HEADER KEYWORDS section below.

BASIC TAR HEADER DESCRIPTION

       Physically, a POSIX.1-1988 tar archive consists of a series of fixed sized blocks of TBLOCK(512) characters.  It contains a series of file
       entries terminated by a logical end-of-archive marker, which consists of two blocks of 512 bytes of binary zeroes.  Each file entry is rep-
       resented by a header block that describes the file followed by one or more blocks with the content of the file. The length of each file	is
       rounded up to a multiple of 512 bytes.

       A  number of TBLOCK sizes blocks are grouped together to a tape record for physical I/O operations. Each record of n blocks is written with
       a single write(2) operation.  On magnetic tapes, this results in a single tape record in case the tape drive is in variable  length  record
       mode.

       The header block is defined in star.h as follows:
       /*
	* POSIX.1-1988 field size values and magic.
	*/
       #define	 TBLOCK 	512
       #define	 NAMSIZ 	100
       #define	 PFXSIZ 	155

       #define	 TMODLEN	8
       #define	 TUIDLEN	8
       #define	 TGIDLEN	8
       #define	 TSIZLEN	12
       #define	 TMTMLEN	12
       #define	 TCKSLEN	8

       #define	 TMAGIC 	"ustar"   /* ustar magic 6 chars + '' */
       #define	 TMAGLEN	6	  /* "ustar" including '' */
       #define	 TVERSION	"00"
       #define	 TVERSLEN	2
       #define	 TUNMLEN	32
       #define	 TGNMLEN	32
       #define	 TDEVLEN	8

       /*
	* POSIX.1-1988 typeflag values
	*/
       #define	 REGTYPE	'0'  /* Regular File	      */
       #define	 AREGTYPE	'' /* Regular File (outdated) */
       #define	 LNKTYPE	'1'  /* Hard Link	      */
       #define	 SYMTYPE	'2'  /* Symbolic Link	      */
       #define	 CHRTYPE	'3'  /* Character Special     */
       #define	 BLKTYPE	'4'  /* Block Special	      */
       #define	 DIRTYPE	'5'  /* Directory	      */
       #define	 FIFOTYPE	'6'  /* FIFO (named pipe)     */
       #define	 CONTTYPE	'7'  /* Contiguous File       */

       /*
	* POSIX.1-2001 typeflag extensions.
	* POSIX.1-2001 calls the extended USTAR format PAX although it is
	* definitely derived from and based on USTAR. The reason may be that
	* POSIX.1-2001 calls the tar program outdated and lists the
	* pax program as the successor.
	*/
       #define	 LF_GHDR	'g'  /* POSIX.1-2001 global extended header */
       #define	 LF_XHDR	'x'  /* POSIX.1-2001 extended header */

       See section EXTENDED TAR (PAX) HEADER KEYWORDS for more information about the structure of a POSIX.1-2001 header.

       /*
	* star/gnu/Sun tar extensions:
	*
	* Note that the standards committee allows only capital A through
	* capital Z for user-defined expansion.  This means that defining
	* something as, say '8' is a *bad* idea.
	*/

       #define	 LF_ACL 	'A'  /* Solaris Access Control List	*/
       #define	 LF_DUMPDIR	'D'  /* GNU dump dir			*/
       #define	 LF_EXTATTR	'E'  /* Solaris Extended Attribute File */
       #define	 LF_META	'I'  /* Inode (metadata only) no file content */
       #define	 LF_LONGLINK	'K'  /* NEXT file has a long linkname	*/
       #define	 LF_LONGNAME	'L'  /* NEXT file has a long name	*/
       #define	 LF_MULTIVOL	'M'  /* Continuation file rest to be skipped */
       #define	 LF_NAMES	'N'  /* OLD GNU for names > 100 characters   */
       #define	 LF_SPARSE	'S'  /* This is for sparse files	*/
       #define	 LF_VOLHDR	'V'  /* tape/volume header Ignore on extraction */
       #define	 LF_VU_XHDR	'X'  /* POSIX.1-2001 xtended (Sun VU version) */

       /*
	* Definitions for the t_mode field
	*/
       #define	 TSUID	   04000     /* Set UID on execution  */
       #define	 TSGID	   02000     /* Set GID on execution  */
       #define	 TSVTX	   01000     /* On directories, restricted deletion flag */
       #define	 TUREAD    00400     /* Read by owner	      */
       #define	 TUWRITE   00200     /* Write by owner special */
       #define	 TUEXEC    00100     /* Execute/search by owner */
       #define	 TGREAD    00040     /* Read by group	      */
       #define	 TGWRITE   00020     /* Write by group	      */
       #define	 TGEXEC    00010     /* Execute/search by group */
       #define	 TOREAD    00004     /* Read by other	      */
       #define	 TOWRITE   00002     /* Write by other	      */
       #define	 TOEXEC    00001     /* Execute/search by other */

       #define	 TALLMODES 07777     /* The low 12 bits       */

       /*
	* This is the ustar (Posix 1003.1) header.
	*/
       struct header {
	    char t_name[NAMSIZ];     /*   0 Filename		   */
	    char t_mode[8];	     /* 100 Permissions 	   */
	    char t_uid[8];	     /* 108 Numerical User ID	   */
	    char t_gid[8];	     /* 116 Numerical Group ID	   */
	    char t_size[12];	     /* 124 Filesize		   */
	    char t_mtime[12];	     /* 136 st_mtime		   */
	    char t_chksum[8];	     /* 148 Checksum		   */
	    char t_typeflag;	     /* 156 Typ of File 	   */
	    char t_linkname[NAMSIZ]; /* 157 Target of Links	   */
	    char t_magic[TMAGLEN];   /* 257 "ustar"		   */
	    char t_version[TVERSLEN]; /* 263 Version fixed to 00   */
	    char t_uname[TUNMLEN];   /* 265 User Name		   */
	    char t_gname[TGNMLEN];   /* 297 Group Name		   */
	    char t_devmajor[8];      /* 329 Major for devices	   */
	    char t_devminor[8];      /* 337 Minor for devices	   */
	    char t_prefix[PFXSIZ];   /* 345 Prefix for t_name	   */
				     /* 500 End 		   */
	    char t_mfill[12];	     /* 500 Filler up to 512	   */
       };

       /*
	* star header specific definitions
	*/
       #define	 STMAGIC	"tar"	  /* star magic */
       #define	 STMAGLEN	4	  /* "tar" including '' */

       /*
	* This is the new (post Posix 1003.1-1988) xstar header
	* defined in 1994.
	*
	* t_prefix[130]    is guaranteed to be ' ' to prevent ustar
	*		   compliant implementations from failing.
	* t_mfill & t_xmagic need to be zero for a 100% ustar compliant
	*		   implementation, so setting t_xmagic to
	*		   "tar" should be avoided in the future.
	*
	* A different method to recognize this format is to verify that
	* t_prefix[130] 	     is equal to ' ' and
	* t_atime[0]/t_ctime[0]      is an octal number and
	* t_atime[11]		     is equal to ' ' and
	* t_ctime[11]		     is equal to ' '.
	*
	* Note that t_atime[11]/t_ctime[11] may be changed in future.
	*/
       struct xstar_header {
	    char t_name[NAMSIZ];     /*   0 Filename		   */
	    char t_mode[8];	     /* 100 Permissions 	   */
	    char t_uid[8];	     /* 108 Numerical User ID	   */
	    char t_gid[8];	     /* 116 Numerical Group ID	   */
	    char t_size[12];	     /* 124 Filesize		   */
	    char t_mtime[12];	     /* 136 st_mtime		   */
	    char t_chksum[8];	     /* 148 Checksum		   */
	    char t_typeflag;	     /* 156 Typ of File 	   */
	    char t_linkname[NAMSIZ]; /* 157 Target of Links	   */
	    char t_magic[TMAGLEN];   /* 257 "ustar"		   */
	    char t_version[TVERSLEN]; /* 263 Version fixed to 00   */
	    char t_uname[TUNMLEN];   /* 265 User Name		   */
	    char t_gname[TGNMLEN];   /* 297 Group Name		   */
	    char t_devmajor[8];      /* 329 Major for devices	   */
	    char t_devminor[8];      /* 337 Minor for devices	   */
	    char t_prefix[131];      /* 345 Prefix for t_name	   */
	    char t_atime[12];	     /* 476 st_atime		   */
	    char t_ctime[12];	     /* 488 st_ctime		   */
	    char t_mfill[8];	     /* 500 Filler up to star magic	*/
	    char t_xmagic[4];	     /* 508 "tar"		   */
       };

       struct sparse {
	    char t_offset[12];
	    char t_numbytes[12];
       };

       #define	 SPARSE_EXT_HDR  21

       struct xstar_ext_header {
	    struct sparse t_sp[21];
	    char t_isextended;
       };

       typedef union hblock {
	    char dummy[TBLOCK];
	    long ldummy[TBLOCK/sizeof (long)]; /* force long alignment */
	    struct header	     dbuf;
	    struct xstar_header      xstar_dbuf;
	    struct xstar_ext_header  xstar_ext_dbuf;
       } TCB;

       For maximum portability, all fields that contain character strings should be limited to use the low 7 bits of a character.

       The  name,  linkname and prefix field contain character strings. The strings are null terminated except when they use the full space of 100
       characters for the name or linkname field or 155 characters for the prefix field.

       If the prefix does not start with a null character, then prefix and name need to be concatenated by using the prefix, followed by  a  slash
       character followed by the name field.  If a null character appears in name or prefix before the maximum size is reached, the field in ques-
       tion is terminated.  This way file names up to 256 characters may be archived.  The prefix is not used together with the linkname field, so
       the maximum length of a link name is 100 characters.

       The fields magic, uname and gname contain null terminated character strings.

       The  version field contains the string "00" without a trailing zero. It cannot be set to different values as POSIX.1-1988 did not specify a
       way to handle different version strings.

       The typeflag field contains a single character.

       All numeric fields contain size-1 leading zero-filled numbers using octal digits.  They are followed by one or more space or  null  charac-
       ters.   All  recent implementations only use one space or null character at the end of a numerical field to get maximum space for the octal
       number.	Star always uses a space character as terminator.  Numeric fields with 8 characters may hold up to 7 octal digits(7777777)  which
       results	is  a maximum value of 2097151.  Numeric fields with 12 characters may hold up to 11 octal digits(77777777777) which results is a
       maximum value of 8589934591.

       Star implements a vendor specific (and thus non-POSIX) extension to put bigger numbers into the numeric fields. This is	done  by  using  a
       base  256 coding.  The top bit of the first character in the appropriate 8 character or 12 character field is set to flag non octal coding.
       If base 256 coding is in use, then all remaining characters are used to code the number. This results in 7 base 256 digits in  8  character
       fields and in 11 base 256 digits in 12 character fields.  All base 256 numbers are two's complement numbers. A base 256 number in a 8 char-
       acter field may hold 56 bits, a base 256 number in a 12 character field may hold 88 bits. This may be extended to 63 bits for  8  character
       fields and to 95 bits for 12 character fields. For a negative number the first character currently is set to a value of 255 (all 8 bits are
       set).  The rightmost character in a 8 or 12 character field contains the least significant base 256 number.  Recent GNU tar versions imple-
       ment the same extension.

       While  the  POSIX  standard  makes  it  obvious	that  the fields mode, uid, gid,  size, chksum, devmajor and devminor should be treated as
       unsigned numbers, there is no such definition for the time field.

       The mode field contains 12 bits holding permissions, see above for the definitions for each of the permission bits.

       The uid and gid fields contain the numerical user id of the file.

       The size field contains the size of the file in characters.  If the tar header is followed by file data, then the amount of data that  fol-
       lows is computed by (size + 511) / 512.

       The  mtime  field  contains  the number of seconds since Jan 1st 1970 00:00 UTC as retrived via stat(2) in st_mtime.  If the mtime fiels is
       assumed to be a signed 33 bit number, the latest representable time is 2106 Feb	7 06:28:15 GMT.

       The chksum field contains a simple checksum over all bytes of the header.  To compute the value, all characters in the header  are  treated
       as unsigned integers and the characters in the chksum field are treated as if they were all spaces. When the computation starts, the check-
       sum value is initialized to 0.

       The typeflag field specifies the type of the file that is archived. If a specific tar implementation does not include support  for  a  spe-
       cific  typeflag value, this implementation will extract the unknown file types as if they were plain files. For this reason, the size field
       for any file type except directories, hard links, symbolic links, character special, block specials and FIFOs must always follow the  rules
       for plain files.

       '0' REGTYPE
	      A regular file.  If the size field is non zero, then file data follows the header.

       '' AREGTYPE
	      For backwards compatibility with pre POSIX.1-1988 tar implementations, a nul character is also recognized as marker for plain files.
	      It is not generated by recent tar implementations.  If the size field is non zero, then file data follows the header.

       '1' LNKTYPE
	      The file is a hard link to another file.	The name of the file that the file is linked to is in the linkname  part  of  the  header.
	      For  tar	archives written by pre POSIX.1-1988 implementations, the size field usually contains the size of the file and needs to be
	      ignored as no data may follow this header type.	For  POSIX.1-1988  compliant  archives,  the  size  field  needs  to  be  0.   For
	      POSIX.1-2001 compliant archives, the size field may be non zero, indicating that file data is included in the archive.

       '2' SYMTYPE
	      The file is a symbolic link to another file.  The name of the file that the file is linked to is in the linkname part of the header.
	      The size field needs to be 0.  No file data may follow the header.

       '3' CHRTYPE
	      A character special file.  The fields devmajor and devminor contain information that defines the file.   The  meaning  of  the  size
	      field is unspecified by the POSIX standard.  No file data may follow the header.

       '4' BLKTYPE
	      A block special file.  The fields devmajor and devminor contain information that defines the file.  The meaning of the size field is
	      unspecified by the POSIX standard.  No file data may follow the header.

       '5' DIRTYPE
	      A directory or sub directory. Old (pre POSIX.1-1988) tar implementations did use the same typeflag value	as  for  plain	files  and
	      added  a	slash to the name.  If the size field is non zero then it indicates the maximum size in characters the system may allocate
	      for this directory. If the size field is 0, then the system shall not limit the size of the directory. On  operating  systems  where
	      the disk allocation is not done on a directory base, the size field is ignored on extraction.  No file data may follow the header.

       '6' FIFOTYPE
	      A  named	pipe.	The meaning of the size field is unspecified by the POSIX standard.  The size field must be ignored on extraction.
	      No file data may follow the header.

       '7' CONTTYPE
	      A contiguous file.  This is a file that gives special performance attributes.  Operating systems that don't support this	file  type
	      extract this file type as plain files.  If the size field is non zero, then file data follows the header.

       'g' GLOBAL POSIX.1-2001 HEADER
	      With  POSIX.1-2001 pax archives, this type defines a global extended header.  The size is always non zero and denotes the sum of the
	      length fields in the extended header data.  The data that follows the header is in the pax extended  header  format.   The  extended
	      header  records  in  this  header  type  affect  all  following files in the archive unless they are overwritten by new values.  See
	      EXTENDED TAR (PAX) HEADER FORMAT section below.

       'x' EXTENDED POSIX.1-2001 HEADER
	      With POSIX.1-2001 pax archives, this type defines an extended header.  The size is always non zero and denotes the sum of the length
	      fields  in  the  extended  header data.  The data that follows the header is in the pax extended header format.  The extended header
	      records in this header type only affect the following file in the archive.  See EXTENDED TAR (PAX) HEADER FORMAT section below.

       'A' - 'Z'
	      Reserved for vendor specific implementations.

       'A'    A Solaris ACL entry as used by the tar implementation from Sun.  The size is always non zero and denotes the length of the data that
	      follows the header.  Star currently is not able to handle this header type.

       'D'    A GNU dump directory.  This header type is not created by star and handled like a directory during an extract operation, so the con-
	      tent is ignored by star.	The size field denotes the length of the data that follows the header.

       'E'    A Solaris Extended Attribute File.  The size field denotes the length of the data that follows the header.  Star	currently  is  not
	      able to handle this header type.

       'I'    A  inode	metadata  entry.   This header type is used by star to archive inode meta data only.  To archive more inode meta data than
	      possible with a POSIX-1.1988 tar header, a header with type 'I' is usually preceded by a 'x' header.  It is  used  with  incremental
	      backups.	The size field holds the length of the file.  No file data follows this header.

       'K'    A  long link name.  Star is able to read and write this type of header with the star, xstar and gnutar formats.  With the xustar and
	      exustar formats, star prefers to store long link names using the POSIX.1-2001 method.  The size is always non zero and  denotes  the
	      length of the long link name including the trailing null byte. The link name is in the data that follows the header.

       'L'    A  long file name.  Star is able to read and write this type of header with the star, xstar and gnutar formats.  With the xustar and
	      exustar formats, star prefers to store long file names using the POSIX.1-2001 method.  The size is always non zero and  denotes  the
	      length of the long file name including the trailing null byte. The file name is in the data that follows the header.

       'M'    A  multi	volume continuation entry.  It is used by star to tell the extraction program via the size field when the next regular ar-
	      chive header will follow.  This allows to start extracting multi volume archives with a volume number greater than one.  It is  used
	      by  GNU tar to verify multi volume continuation volumes.	Other fields in the GNU multi volume continuation header are a result of a
	      GNU tar miss conception and cannot be used in a reliable tar implementation.  If the size field is non zero the data  following  the
	      header  is  skipped  by star if the volume that starts with it is mounted as the first volume.  This header is ignored if the volume
	      that starts with it is mounted as continuation volume.

       'N'    An outdated linktype used by old GNU tar versions to store long file names.  This type is unsupported by star.

       'S'    A sparse file.  This header type is used by star and GNU tar.  A sparse header is used instead of a plain file header  to  denote  a
	      sparse  file that follows. Directly after the header, a list of sparse hole descriptors follows followed by the compacted file data.
	      With star formats, the size field holds a size that represents the sum of the sparse hole descriptors plus the size of the compacted
	      file  data.  This  allows  other	tar  implementations  to correctly skip to the next tar header.  With GNU tar, up to 4 sparse hole
	      descriptors fit into the sparse header.  Additional hole descriptors are not needed if the file has less than  4	holes.	 With  GNU
	      tar,  the size field breaks general tar header rules in case more than 4 sparse hole descriptors are used and is meaningless because
	      the size of the additional sparse hole descriptors used by GNU tar does not count and cannot be determined before parsing all sparse
	      hole descriptors.

       'V'    A  volume  header.   The name field is is used to hold the volume name.  Star uses the atime field to hold the volume number in case
	      there is no POSIX.1-2001 extended header.  This header type is used by star and GNU tar.	If the size field is  non  zero  the  data
	      following the header is skipped by star.

       'X'    A vendor unique variant of the POSIX.1-2001 extended header type.  It has been implemented by Sun many years before the POSIX.1-2001
	      standard has been approved.  See also the typeflag 'x' header type.  Star is able to read and write this type of header.

EXTENDED TAR (PAX) HEADER STRUCTURE
       Block type			     Description

       Ustar Header [typeflag='g']	Global Extended Header
       Global Extended Data
       Ustar Header [typeflag='x']	   Extended Header
       Extended Data
       Ustar header [typeflag='0']    File with Extended Header
       Data for File #1
       Ustar header [typeflag='0']   File without Extended Header
       Data for File #2
       Block of binary zeroes		   First EOF Block
       Block of binary zeroes		   Second EOF Block

EXTENDED TAR (PAX) HEADER FORMAT
       The data block that follows a tar archive header with typeflag 'g' or 'x' contains one or more records in the following format:

	      "%d %s=%s
", <length>, <keyword>, <value>

       Each record starts with a a decimal length field. The length includes the total size of a record including the length field itself and  the
       trailing new line.

       The  keyword  may  not include an equal sign.  All keywords beginning with lower case letters and digits are reserved for future use by the
       POSIX standard.

       If the value field is of zero length, it deletes any header field of the same name that is in effect from the same extended header or  from
       a previous global header.

       Null characters do not delimit any value. The data used for value is only limited by its implicit length.

EXTENDED TAR (PAX) HEADER KEYWORDS
       POSIX.1-2001  extended  pax  header  keywords. All numerical values are represented as decimal strings.	All texts are represented as 7-bit
       ascii or UTF-8:

       atime  The time from st_atime in sub second granularity.  Star currently supports a nanosecond granularity.

       charset
	      The name of the character set used to encode the data in the following file(s).

	      The following values are supported for charset:

	      ISO-IR 646 1990	       SO/IEC 646:1990

	      ISO-IR 8859 1 1998       ISO/IEC 8859-1:1998

	      ISO-IR 8859 2 1998       ISO/IEC 8859-2:1998

	      ISO-IR 8859 3 1998       ISO/IEC 8859-3:1998

	      ISO-IR 8859 4 1998       ISO/IEC 8859-4:1998

	      ISO-IR 8859 5 1998       ISO/IEC 8859-5:1998

	      ISO-IR 8859 6 1998       ISO/IEC 8859-6:1998

	      ISO-IR 8859 7 1998       ISO/IEC 8859-7:1998

	      ISO-IR 8859 8 1998       ISO/IEC 8859-8:1998

	      ISO-IR 8859 9 1998       ISO/IEC 8859-9:1998

	      ISO-IR 8859 10 1998      ISO/IEC 8859-10:1998

	      ISO-IR 8859 11 1998      ISO/IEC 8859-11:1998

	      ISO-IR 8859 12 1998      ISO/IEC 8859-12:1998

	      ISO-IR 8859 13 1998      ISO/IEC 8859-13:1998

	      ISO-IR 8859 14 1998      ISO/IEC 8859-14:1998

	      ISO-IR 8859 15 1998      ISO/IEC 8859-15:1998

	      ISO-IR 10646 2000        ISO/IEC 10646:2000

	      ISO-IR 10646 2000 UTF-8  ISO/IEC 10646, UTF-8 encoding

	      BINARY		       None

	      This keyword is currently ignored by star.

       comment
	      Any number of characters that should be treated as comment.  Star ignores the comment as documented by the POSIX standard.

       ctime  The time from st_ctime in sub second granularity.  Star currently supports a nanosecond granularity.

       gid    The group ID of the group that owns the file.  The argument is a decimal number.	This field is used if the group ID of  a  file	is
	      greater than 2097151 (octal 7777777).

       gname  The  group  name of the following file(s) coded in UTF-8 if the group name does not fit into 32 characters or cannot be expressed in
	      7-Bit ASCII.

       hdrcharset
	      The name of the character set used to encode the data for the gname, linkpath, path and uname fields in  the  POSIX.1-2001  extended
	      header records.

	      The following values are supported for hdrcharset:

	      ISO-IR 10646 2000 UTF-8  ISO/IEC 10646, UTF-8 encoding

	      BINARY		       None

	      This keyword is currently ignored by star.

       linkpath
	      The name of the linkpath coded in UTF-8 if it is longer than 100 characters or cannot be expressed in 7-Bit ASCII.

       mtime  The time from st_mtime in sub second granularity.  Star currently supports a nanosecond granularity.

       path   The  name  of  the  linkpath coded in UTF-8 if it does not fit into 100 characters + 155 characters prefix or cannot be expressed in
	      7-Bit ASCII.

       realtime.any
	      The keywords prefixed by realtime.  are reserved for future standardization.

       security.any
	      The keywords prefixed by security.  are reserved for future standardization.

       size   The size of the file as decimal number if the file size is greater than 8589934591 (octal 77777777777).  The size  keyword  may  not
	      refer to the real file size but is related to the size if the file in the archive.  See also SCHILY.realsize for more information.

       uid    The  uid	ID  of	the  group  that  owns the file.  The argument is a decimal number.  This field is used if the uid ID of a file is
	      greater than 2097151 (octal 7777777).

       uname  The user name of the following file(s) coded in UTF-8 if the user name does not fit into 32 characters or  cannot  be  expressed	in
	      7-Bit ASCII.

       VENDOR.keyword
	      Any keyword that starts with a vendor name in capital letters is reserved for vendor specific extensions by the standard.  Star uses
	      a lot of these vendor specific extension. See below for more informations.

SCHILY PAX EXTENSION KEYWORDS

       Star uses own vendor specific extensions. The SCHILY vendor specific extended pax header keywords are:

       SCHILY.acl.access
	      The ACL for a file.

	      Since no official backup format for POSIX  access  control  lists  has  been  defined,  star  uses  the  vendor  defined	attributes
	      SCHILY.acl.access  and SCHILY.acl.default for storing the ACL and Default ACL of a file, respectively.  The access control lists are
	      stored in the short text form as defined in POSIX 1003.1e draft standard 17.

	      Note that the POSIX 1003.1e draft has been withdrawn in 1997 but some operating systems still support it with some filesystems.

	      To each named user ACL entry a fourth colon separated field field containing the user identifier (UID) of  the  associated  user	is
	      appended.  To each named group entry a fourth colon separated field containing the group identifier (GID) of the associated group is
	      appended.  (POSIX 1003.1e draft standard 17 allows to add fields to ACL entries.)

	      This is an example of the format used for SCHILY.acl.access (a space has been inserted after the equal sign  and	lines  are  broken
	      [marked with '' ] for readability, additional fields in bold):

	      SCHILY.acl.access= user::rwx,user:lisa:r-x:502, 
				 group::r-x,group:toolies:rwx:102, 
				 mask::rwx,other::r--x

	      The  numerical  user and group identifiers are essential when restoring a system completely from a backup, as initially the name-to-
	      identifier mappings may not be available, and then file ownership restoration would not work.

	      As the archive format that is used for backing up access control lists is compatible with the pax archive format,  archives  created
	      that  way  can be restored by star or a POSIX.1-2001 compliant pax.  Note that programs other than star will ignore the ACL informa-
	      tion.

       SCHILY.acl.default
	      The default ACL for a file. See SCHILY.acl.access for more information.

	      This is an example of the format used for SCHILY.acl.default (a space has been inserted after the equal sign and	lines  are  broken
	      [marked with '' ] for readability, additional fields in bold):

	      SCHILY.acl.default= user::rwx,user:lisa:r-x:502, 
				  group::r-x,mask::r-x,other::r-x

       SCHILY.acl.type
	      The ACL type used for coding access control lists.

	      The following ACL types are possible:

	      POSIX draft
		     ACLs as defined in POSIX 1003.1e draft standard 17.

	      NFSv4  ACLs as used by NFSv4, NTFS and ZFS.

       Star currently only implements POSIX draft ACLs.  If the SCHILY.acl.type keyword is missing, POSIX draft ACLs are asumed.

       SCHILY.ddev
	      The device ids for names used is the SCHILY.dir dump directory list from st_dev of the file as decimal number.  The SCHILY.ddev key-
	      word is followed by a space separated list of device id numbers. Each corresponds exactly to a name in the list found in SCHILY.dir.
	      If  a  specific  device id number is repeated, a comma (,) without a following space may be use to denote that the current device id
	      number is identical to the previous number.  This keyword is used in dump mode.  This keyword is not yet implemented.

	      The value is a signed int.  An implementation should be able to handle at least 64 bit  values.	Note  that  the  value	is  signed
	      because POSIX does not specify more than the type should be an int.

       SCHILY.dev
	      The device id from st_dev of the file as decimal number.	This keyword is used in dump mode.

	      The  value  is  a  signed  int.	An  implementation should be able to handle at least 64 bit values.  Note that the value is signed
	      because POSIX does not specify more than the type should be an int.

       SCHILY.devmajor
	      The device major number of the file if it is a character or block special file.  The argument is a decimal number.   This  field	is
	      used if the device major of the file is greater than 2097151 (octal 7777777).

	      The  value  is  a  signed  int.	An  implementation should be able to handle at least 64 bit values.  Note that the value is signed
	      because POSIX does not specify more than the type should be an int.

       SCHILY.devminor
	      The device minor number of the file if it is a character or block special file.  The argument is a decimal number.   This  field	is
	      used if the device minor of the file is greater than 2097151 (octal 7777777).

	      The  value  is  a  signed  int.	An  implementation should be able to handle at least 64 bit values.  Note that the value is signed
	      because POSIX does not specify more than the type should be an int.

       SCHILY.dino
	      The inode numbers for names used is the SCHILY.dir dump directory list from st_ino of the file as decimal number.   The  SCHILY.dino
	      keyword  is followed by a space separated list of inode numbers. Each corresponds exactly to a name in the list found in SCHILY.dir.
	      This keyword is used in dump mode.

	      The values are unsigned int.  An implementation should be able to handle at least 64 bit unsigned values.

       SCHILY.dir
	      A list of filenames (the content) for the current directory.  The names are coded in UTF-8.  Each file name is prefixed by a  single
	      character  that  is  used  as a flag.  Each file name is limited by a null character.  The null character is directly followed by he
	      flag character for the next file name in case the list is not terminated by the current file name.  The flag character must not be a
	      null character.  By default, a ^A (octal 001) is used.  The following flags are defined:

	      00   This is the list terminator character - the second null byte, see below.

	      ^A     The default flag that is used in case the dump dir features have not been active.

	      Y      A non directory file that is in the current (incremental) dump.

	      N      A non directory file that is not in the current (incremental) dump.

	      D      A directory that is in the current (incremental) dump.

	      d      A directory that is not in the current (incremental) dump.

	      The list is terminated by two successive null bytes.  The first is the null byte for the last file name.	The second null byte is at
	      the position where a flag character would be expected, it acts ad a list terminator. The length tag for the SCHILY.dir data includes
	      both null bytes.

	      If  a dump mode has been selected that writes compact complete directory information to the beginning of the archive, the flag char-
	      acter may contain values different from ^A.  Star implementations at least up to star-1.5.1 do not use the feature  to  tag  entries
	      and  use the default entry 01 (^A) for all files.  Tar implementations that like to read archives that use the SCHILY.dir keyword,
	      shall not rely on values other than 00 (^@) or 01 (^A).

	      This keyword is used in dump mode.

       SCHILY.fflags
	      A textual version of the BSD or Linux extended file flags.

	      The following flags are defined by star:

	      arch	     set the archived flag (super-user only).

	      archived	     Alias for arch.

	      nodump	     set the nodump flag (owner or super-user).

	      opaque	     set the opaque flag (owner or super-user).

	      sappnd	     set the system append-only flag (super-user only).

	      sappend	     Alias for sappnd.

	      schg	     set the system immutable flag (super-user only).

	      schange	     Alias for schg.

	      simmutable     Alias for schg.

	      sunlnk	     set the system undeletable flag (super-user only).

	      sunlink	     Alias for sunlnk.

	      uappnd	     set the user append-only flag (owner or super-user).

	      uappend	     Alias for uappnd.

	      uchg	     set the user immutable flag (owner or super-user).

	      uchange	     Alias for uchg.

	      uimmutable     Alias for uchg.

	      uunlnk	     set the user undeletable flag (owner or super-user).

	      uunlink	     Alias for uunlnk.

	      The following flags are only available on Linux:

	      compress	     Set the Linux ext3 journal data flag (owner or super-user).

	      journal-data   Set the Linux ext3 journal data flag (super-user only).

	      noatime	     Set the Linux ext3 no access time flag (owner or super-user).

	      secdel	     Set the Linux ext3 secure deletion (purge before delete) flag (owner or super-user).

	      sync	     Set the Linux ext3 sync flag (owner or super-user).

	      undel	     Set the Linux ext3 "allow unrm" flag (owner or super-user).

       SCHILY.filetype
	      A textual version of the real file type of the file.  The following names are used:

	      unallocated	      An unknown file type that may be a result of a unlink(2) operation.  This should never happen.

	      regular		      A regular file.

	      contiguous	      A contiguous file. On operating systems or file systems that don't support this file  type,  it  is  handled
				      like a regular file.

	      symlink		      A symbolic link to any file type.

	      directory 	      A directory.

	      character special       A character special file.

	      block special	      A block special file.

	      fifo		      A named pipe.

	      socket		      A UNIX domain socket.

	      mpx character special   A multiplexed character special file.

	      mpx block special       A multiplexed block special file.

	      XENIX nsem	      A XENIX named semaphore.

	      XENIX nshd	      XENIX shared data.

	      door		      A Solaris door.

	      eventcount	      A UNOS event count.

	      whiteout		      A BSD whiteout directory entry.

	      sparse		      A sparse regular file.

	      volheader 	      A volume header.

	      unknown/bad	      Any other unknown file type.  This should never happen.

       SCHILY.ino
	      The inode number from st_ino of the file as decimal number.  This keyword is used in dump mode.

	      The value is an unsigned int.  An implementation should be able to handle at least 64 bit unsigned values.

       SCHILY.nlink
	      The link count of the file as decimal number.  This keyword is used in dump mode.

	      The value is an unsigned int.  An implementation should be able to handle at least 32 bit unsigned values.

       SCHILY.offset
	      The offset value for a multi volume continuation header.	This keyword is used with multi volume continuation headers.  Multi volume
	      continuation headers are used to allow to start reading a multi volume archive past the first volume.

	      SCHILY.offset specifies the byte offset within a file that was split across volumes as a result of a multi volume media change oper-
	      ation.

	      The value is an unsigned int.  An implementation should be able to handle at least 64 bit unsigned values.

       SCHILY.realsize
	      The real size of the file as decimal number.  This keyword is used if the real size of the file differs from the visible size of the
	      file in the archive.  The real file size differs from the size in the archive if the file type is sparse or if the file is a contin-
	      uation  file  on	a multi volume archive.  In case the SCHILY.realsize keyword is needed, it must be past any size keyword in case a
	      size keyword is also present.

	      As sparse files allocate less space on tape than a regular file and as a continued file that started on a previous volume only holds
	      parts of the file, the SCHILY.realsize keyword holds a bigger number than the size keyword.

	      The value is an unsigned int.  An implementation should be able to handle at least 64 bit unsigned values.

       SCHILY.tarfiletype
	      The following additional file types are used in SCHILY.tarfiletype:

	      hardlink
		     A hard link to any file type.

	      dumpdir
		     A directory with dump entries

	      multivol continuation
		     A multi volume continuation for any file type.

	      meta   A meta entry (inode meta data only) for any file type.

       SCHILY.xattr.attr
	      A  POSIX.1-2001  coded  version  of  the Linux extended file attributes.	Linux extended file attributes are name/value pairs. Every
	      attribute name results in a SCHILY.xattr.name tag and the value of the extended attribute is used as the value of  the  POSIX.1-2001
	      header  tag.   Note that this way of coding is not portable across platforms.  A version for BSD may be created but Solaris includes
	      far more features with extended attribute files than Linux does.

	      A future version of star will implement a similar method as the tar program on Solaris currently uses. When this	implementation	is
	      ready, the SCHILY.xattr.name feature may be removed in favor of a truly portable implementation that supports Solaris also.

SCHILY 'G'LOBAL PAX EXTENSION KEYWORDS
       The following star vendor unique extensions may only appear in 'g'lobal extended pax headers:

       SCHILY.archtype
	      The  textual  version of the archive type used.  The textual values used for SCHILY.archtype are the same names that are used in the
	      star command line options to set up a specific archive type.

	      The following values may currently appear in a global extended header:

	      xustar	     'xstar' format without "tar" signature at header offset 508.

	      exustar	     'xustar' format variant that always includes x-headers and g-headers.

	      A complete tar implementation must be prepared to handle all archives names as documented in star(1).

	      In order to allow archive type recognition from this keyword, the minimum tape block size must be 2x512 bytes (1024 bytes)  and  the
	      SCHILY.archtype  keyword	needs  to  be  in the first 512 bytes of the content of the first 'g'lobal pax header. Then the first tape
	      block may be scanned to recognize the archive type.

       SCHILY.release
	      The textual version of the star version string and the platform name where this star has been compiled.  The same text appears  when
	      calling star -version.

	      Other implementations may use a version string that does not start with the text star.

       SCHILY.volhdr.blockoff
	      This keyword is used for multi volume archives.  It represents the offset within the whole archive expressed in 512 byte units.

	      The  value  is an unsigned int with a valid range between 1 and infinity. An implementation should be able to handle at least 64 bit
	      unsigned values.

       SCHILY.volhdr.blocksize
	      The tape blocksize expressed in 512 byte units that was used when writing the archive.

	      The value is an unsigned int with a valid range between 1 and infinity. An implementation should be able to handle at least  31  bit
	      unsigned values.

       SCHILY.volhdr.cwd
	      This  keyword  is  used  in dump mode.  It is only emitted in case the fs-name= option of star was used to overwrite the SCHILY.vol-
	      hdr.filesys value.  If SCHILY.volhdr.cwd is present, it contains the real backup working directory.

	      Overwriting SCHILY.volhdr.filesys is needed when backups are run on file system snapshots rather than on the real file system.

       SCHILY.volhdr.device
	      This keyword is used in dump mode.  It represents the name of the device that holds the file system data. For disk based	file  sys-
	      tems, this is the device name of the mounted device.

	      This keyword is optional. It helps to correctly identify the file system from which this dump has been made.

       SCHILY.volhdr.dumpdate
	      This keyword is used in dump mode.  It represents the time the current dump did start.

       SCHILY.volhdr.dumplevel
	      This keyword is used in dump mode.  It represents the level of the current dump.	Dump levels are small numbers, the lowest possible
	      number is 0.  Dump level 0 represents a full backup.  Dump level 1 represents a backup that contains  all  changes  that	did  occur
	      since the last level 0 dump.  Dump level 2 represents a backup that contains all changes that did occur since the last level 1 dump.
	      Star does not specify a maximum allowed dump level but you should try to keep the numbers less than 100.

	      The value is an unsigned int with a valid range between 0 and at least 100.

       SCHILY.volhdr.dumptype
	      This keyword is used in dump mode.  If the dump is a complete dump of a file system (i.e. no files are excluded via  command  line),
	      then the argument is the text full, else the argument is the text partial.

       SCHILY.volhdr.filesys
	      This  keyword  is  used in dump mode.  It represents the top level directory for the file system from which this dump has been made.
	      If the dump represents a dump that has an associated level, then the this directory needs to be identical to the root  directory	of
	      this file system which is the mount point.

       SCHILY.volhdr.hostname
	      This keyword is used in dump mode.  The value is retrieved from gethostname(3) or uname(2).

       SCHILY.volhdr.label
	      The textual volume label.  The volume label must be identical within a set of multi volume archives.

       SCHILY.volhdr.refdate
	      This  keyword  is used in dump mode if the current dump is an incremental dump with a level > 0.	It represents the time the related
	      dump did start.

       SCHILY.volhdr.reflevel
	      This keyword is used in dump mode if the current dump is an incremental dump with a level > 0.   It  represents  the  level  of  the
	      related  dump.   The related dump is the last dump with a level that is lower that the level of this dump.  If a dump with the level
	      of the current dump -1 exists, then this is the related dump level. Otherwise, the dump level is	decremented  until  a  valid  dump
	      level could be found in the dump database.

	      The value is an unsigned int with a valid range between 0 and at least 100.

       SCHILY.volhdr.tapesize
	      This  keyword is used for multi volume archives and may be used to verify the volume size on read back.  It represents the tape size
	      expressed in 512 byte units.  This keyword is set in multi volume mode if the size of the tape was not autodetected but set  from  a
	      command line option.

	      The  value  is an unsigned int with a valid range between 1 and infinity. An implementation should be able to handle at least 64 bit
	      unsigned values.

       SCHILY.volhdr.volume
	      This keyword is used for multi volume archives.  It represents the volume number within a volume set.  The number used for the first
	      volume is 1.

	      The  value  is an unsigned int with a valid range between 1 and infinity. An implementation should be able to handle at least 31 bit
	      unsigned values.

MULTI VOLUME ARCHIVE HANDLING

       To be documented in the future.

SEE ALSO

NOTES

BUGS

AUTHOR

Joerg Schilling 						     11/12/12								  STAR(4L)