NAME
tar — format of tar tape archive
DESCRIPTION
The
header
structure produced by
tar
(see
tar(1))
is as follows
(the array size defined by the constants is shown on the right):
struct {
char name[NAMSIZ]; (100)
char mode[MODE_SZ]; (8)
char uid[UID_SZ]; (8)
char gid[GID_SZ]; (8)
char size[SIZE_SZ]; (12)
char mtime[MTIME_SZ]; (12)
char chksum[CHKSUM_SZ]; (8)
char typeflag;
char linkname[NAMSIZ]; (100)
char magic[MAGIC_SZ]; (6)
char version[VERSION_SZ]; (2)
char uname[UNAME_SZ]; (32)
char gname[GNAME_SZ]; (32)
char devmajor[DEV_SZ]; (8)
char devminor[DEV_SZ]; (8)
char prefix[PREFIX_SZ]; (155)
} dbuf;
All characters are represented in
ASCII.
There is no padding used in the header block; all fields are contiguous.
The fields
magic,
uname,
and
gname
are null-terminated character strings.
The fields
name,
linkname,
and
prefix
are null-terminated character strings
except when all characters in the array
contain non-null characters, including the last character.
The
version
field is two bytes containing the characters
00
(zero-zero).
The
typeflag
contains a single character.
All other fields are leading-zero-filled octal numbers in
ASCII.
Each numeric field is terminated by one or more space or null characters.
The
name
and the
prefix
fields produce the pathname of the file.
The hierarchical relationship of the file
is retained by specifying the pathname as a path prefix,
with a slash character and filename as the suffix.
If the
prefix
contains non-null characters,
prefix,
a slash character, and
name
are concatenated without modification or addition of new characters
to produce a new pathname.
In this manner, pathnames of at most 256 characters can be supported.
If a pathname does not fit in the space provided,
the format-creating utility notifies the user of the error,
and no attempt is made to store any part of the file,
header, or data on the medium.
STANDARDS CONFORMANCE
tar: XPG4, FIPS 151-2, POSIX.1
Printable version
