HP-UX Reference (11i v3 07/02) - 1 User Commands N-Z (vol 2)

p
pax(1) pax(1)
chksum
The octal value of the simple sum of all bytes in the header logical record. Each bytes in the header
shall be treated as an unsigned value. When calculating the checksum, the chksum field is treated as
if it were all spaces.
magic
The magic field is the specification that this archive was output in this archive format. If this field con-
tains ustar (the five characters from the ISO/IEC 646:1991 standard IRV shown followed by NUL),
the uname and gname fields shall contain the ISO/IEC 646:1991 standard IRV representation of the
owner and group of the file, respectively. When the file is restored by a privileged, protection-
preserving version of the utility, the user and group databases shall be scanned for these names. If
found, the user and group IDs contained within these files shall be used rather than the values con-
tained within the uid and gid fields.
version
The version field is two bytes containing the characters "00" (zero-zero).
pax Interchange Format
A pax archive tape or file produced in the -x pax format shall contain a series of blocks. The physical
layout of the archive shall be identical to the ustar format described in ustar Interchange Format. Each file
archived shall be represented by the following sequence:
1. An optional header block with extended header records. This header is of the form described in pax
Header Block with a
typeflag value of x or g. The extended header records, described in pax
Extended Header shall be included as the data for this header block.
2. A header block that describes the file. Any fields in the preceding optional extended header shall over-
ride the associated fields in this header block for this file.
3. Zero or more blocks that contain the contents of the file.
At the end of the archive file there shall be two 512-byte blocks filled with binary zeros, interpreted as an
end-of-archive indicator.
pax Header Block
The
pax header block shall be identical to the ustar header block described in ustar Interchange Format
except that two additional typeflag values are defined:
x Represents extended header records for the following file in the archive (which shall have its own
ustar header block). The format of these extended header records shall be as described in the pax
Extended Header section of this manpage.
g Represents global extended header records for the following files in the archive. The format of these
extended header records shall be as described in pax Extended Header. Each value shall affect all
subsequent files that do not override that value in their own extended header record and until another
global extended header record is reached that provides another value for the same field. The
typeflag g global headers should not be used with interchange media that could suffer partial
data loss in transporting the archive.
For both of these types, the size field shall be the size of the extended header records in bytes. The other
fields in the header block are not meaningful to this version of the pax utility.
A further difference from the ustar header block is that data blocks for files of typeflag 1 (the digit one)
(hard link) may be included, which means that the size field may be greater than zero. Archives created by
pax -o linkdata shall include these data blocks with the hard links.
pax Extended Header
A pax extended header contains values that are inappropriate for the ustar header block because of lim-
itations in that format: fields representing file attributes not described in the ustar header, and fields
whose format or length do not fit the requirements of the ustar header. The values in an extended
header add attributes to the following file (or files; see the description of the typeflag g header block)
or override values in the following header block(s), as indicated in the following list of keywords.
An extended header shall consist of one or more records, each constructed as follows:
%d %s=%s\n,length,keyword,value
The keyword field shall be one of the entries from the following list. A keyword shall not include an equals
sign. In the following list, the notations "file(s)" or "block(s)" are used to acknowledge that a keyword affects
114 Hewlett-Packard Company − 10 − HP-UX 11i Version 3: February 2007