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Diffstat (limited to 'docs/tar_pax.txt')
| -rw-r--r-- | docs/tar_pax.txt | 232 |
1 files changed, 116 insertions, 116 deletions
diff --git a/docs/tar_pax.txt b/docs/tar_pax.txt index 8a3f1e7..e56c27b 100644 --- a/docs/tar_pax.txt +++ b/docs/tar_pax.txt @@ -4,197 +4,197 @@ for everything (filename, uid, filesize etc) which can overflow. pax Header Block -The pax header block shall be identical to the ustar header block -described in ustar Interchange Format, except that two additional +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 + Represents extended header records for the following file in the archive (which shall have its own ustar header block). g - Represents global extended header records for the following -files in the archive. 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 + Represents global extended header records for the following +files in the archive. 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 octets. The other fields in the header -block are not meaningful to this version of the pax utility. -However, if this archive is read by a pax utility conforming to -the ISO POSIX-2:1993 standard, the header block fields are used to -create a regular file that contains the extended header records as -data. Therefore, header block field values should be selected to +For both of these types, the size field shall be the size of the +extended header records in octets. The other fields in the header +block are not meaningful to this version of the pax utility. +However, if this archive is read by a pax utility conforming to +the ISO POSIX-2:1993 standard, the header block fields are used to +create a regular file that contains the extended header records as +data. Therefore, header block field values should be selected to provide reasonable file access to this regular file. -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 +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. pax Extended Header -An extended header shall consist of one or more records, each +An extended header shall consist of one or more records, each constructed as follows: "%d %s=%s\n", <length>, <keyword>, <value> -The <length> field shall be the decimal length of the extended -header record in octets, including length string itself and the +The <length> field shall be the decimal length of the extended +header record in octets, including length string itself and the trailing <newline>. [skip] atime - The file access time for the following file(s), equivalent to -the value of the st_atime member of the stat structure for a file, -as described by the stat() function. The access time shall be -restored if the process has the appropriate privilege required to -do so. The format of the <value> shall be as described in pax + The file access time for the following file(s), equivalent to +the value of the st_atime member of the stat structure for a file, +as described by the stat() function. The access time shall be +restored if the process has the appropriate privilege required to +do so. The format of the <value> shall be as described in pax Extended Header File Times. charset - The name of the character set used to encode the data in the + The name of the character set used to encode the data in the following file(s). - The encoding is included in an extended header for information -only; when pax is used as described in IEEE Std 1003.1-2001, it -shall not translate the file data into any other encoding. The + The encoding is included in an extended header for information +only; when pax is used as described in IEEE Std 1003.1-2001, it +shall not translate the file data into any other encoding. The BINARY entry indicates unencoded binary data. - When used in write or copy mode, it is implementation-defined + When used in write or copy mode, it is implementation-defined whether pax includes a charset extended header record for a file. comment - A series of characters used as a comment. All characters in + A series of characters used as a comment. All characters in the <value> field shall be ignored by pax. gid - The group ID of the group that owns the file, expressed as a -decimal number using digits from the ISO/IEC 646:1991 standard. -This record shall override the gid field in the following header -block(s). When used in write or copy mode, pax shall include a gid -extended header record for each file whose group ID is greater + The group ID of the group that owns the file, expressed as a +decimal number using digits from the ISO/IEC 646:1991 standard. +This record shall override the gid field in the following header +block(s). When used in write or copy mode, pax shall include a gid +extended header record for each file whose group ID is greater than 2097151 (octal 7777777). gname - The group of the file(s), formatted as a group name in the -group database. This record shall override the gid and gname -fields in the following header block(s), and any gid extended -header record. When used in read, copy, or list mode, pax shall -translate the name from the UTF-8 encoding in the header record to -the character set appropriate for the group database on the -receiving system. If any of the UTF-8 characters cannot be -translated, and if the -o invalid= UTF-8 option is not specified, -the results are implementation-defined. When used in write or copy -mode, pax shall include a gname extended header record for each -file whose group name cannot be represented entirely with the + The group of the file(s), formatted as a group name in the +group database. This record shall override the gid and gname +fields in the following header block(s), and any gid extended +header record. When used in read, copy, or list mode, pax shall +translate the name from the UTF-8 encoding in the header record to +the character set appropriate for the group database on the +receiving system. If any of the UTF-8 characters cannot be +translated, and if the -o invalid= UTF-8 option is not specified, +the results are implementation-defined. When used in write or copy +mode, pax shall include a gname extended header record for each +file whose group name cannot be represented entirely with the letters and digits of the portable character set. linkpath - The pathname of a link being created to another file, of any -type, previously archived. This record shall override the linkname -field in the following ustar header block(s). The following ustar -header block shall determine the type of link created. If typeflag -of the following header block is 1, it shall be a hard link. If -typeflag is 2, it shall be a symbolic link and the linkpath value -shall be the contents of the symbolic link. The pax utility shall -translate the name of the link (contents of the symbolic link) -from the UTF-8 encoding to the character set appropriate for the -local file system. When used in write or copy mode, pax shall -include a linkpath extended header record for each link whose -pathname cannot be represented entirely with the members of the + The pathname of a link being created to another file, of any +type, previously archived. This record shall override the linkname +field in the following ustar header block(s). The following ustar +header block shall determine the type of link created. If typeflag +of the following header block is 1, it shall be a hard link. If +typeflag is 2, it shall be a symbolic link and the linkpath value +shall be the contents of the symbolic link. The pax utility shall +translate the name of the link (contents of the symbolic link) +from the UTF-8 encoding to the character set appropriate for the +local file system. When used in write or copy mode, pax shall +include a linkpath extended header record for each link whose +pathname cannot be represented entirely with the members of the portable character set other than NUL. mtime - The file modification time of the following file(s), -equivalent to the value of the st_mtime member of the stat -structure for a file, as described in the stat() function. This -record shall override the mtime field in the following header -block(s). The modification time shall be restored if the process -has the appropriate privilege required to do so. The format of the + The file modification time of the following file(s), +equivalent to the value of the st_mtime member of the stat +structure for a file, as described in the stat() function. This +record shall override the mtime field in the following header +block(s). The modification time shall be restored if the process +has the appropriate privilege required to do so. The format of the <value> shall be as described in pax Extended Header File Times. path - The pathname of the following file(s). This record shall -override the name and prefix fields in the following header -block(s). The pax utility shall translate the pathname of the file -from the UTF-8 encoding to the character set appropriate for the + The pathname of the following file(s). This record shall +override the name and prefix fields in the following header +block(s). The pax utility shall translate the pathname of the file +from the UTF-8 encoding to the character set appropriate for the local file system. - When used in write or copy mode, pax shall include a path -extended header record for each file whose pathname cannot be -represented entirely with the members of the portable character + When used in write or copy mode, pax shall include a path +extended header record for each file whose pathname cannot be +represented entirely with the members of the portable character set other than NUL. realtime.any - The keywords prefixed by "realtime." are reserved for future + The keywords prefixed by "realtime." are reserved for future standardization. security.any - The keywords prefixed by "security." are reserved for future + The keywords prefixed by "security." are reserved for future standardization. size - The size of the file in octets, expressed as a decimal number -using digits from the ISO/IEC 646:1991 standard. This record shall -override the size field in the following header block(s). When -used in write or copy mode, pax shall include a size extended -header record for each file with a size value greater than + The size of the file in octets, expressed as a decimal number +using digits from the ISO/IEC 646:1991 standard. This record shall +override the size field in the following header block(s). When +used in write or copy mode, pax shall include a size extended +header record for each file with a size value greater than 8589934591 (octal 77777777777). uid - The user ID of the file owner, expressed as a decimal number -using digits from the ISO/IEC 646:1991 standard. This record shall -override the uid field in the following header block(s). When used -in write or copy mode, pax shall include a uid extended header -record for each file whose owner ID is greater than 2097151 (octal + The user ID of the file owner, expressed as a decimal number +using digits from the ISO/IEC 646:1991 standard. This record shall +override the uid field in the following header block(s). When used +in write or copy mode, pax shall include a uid extended header +record for each file whose owner ID is greater than 2097151 (octal 7777777). uname - The owner of the following file(s), formatted as a user name -in the user database. This record shall override the uid and uname -fields in the following header block(s), and any uid extended -header record. When used in read, copy, or list mode, pax shall -translate the name from the UTF-8 encoding in the header record to -the character set appropriate for the user database on the -receiving system. If any of the UTF-8 characters cannot be -translated, and if the -o invalid= UTF-8 option is not specified, -the results are implementation-defined. When used in write or copy -mode, pax shall include a uname extended header record for each -file whose user name cannot be represented entirely with the + The owner of the following file(s), formatted as a user name +in the user database. This record shall override the uid and uname +fields in the following header block(s), and any uid extended +header record. When used in read, copy, or list mode, pax shall +translate the name from the UTF-8 encoding in the header record to +the character set appropriate for the user database on the +receiving system. If any of the UTF-8 characters cannot be +translated, and if the -o invalid= UTF-8 option is not specified, +the results are implementation-defined. When used in write or copy +mode, pax shall include a uname extended header record for each +file whose user name cannot be represented entirely with the letters and digits of the portable character set. -If the <value> field is zero length, it shall delete any header -block field, previously entered extended header value, or global +If the <value> field is zero length, it shall delete any header +block field, previously entered extended header value, or global extended header value of the same name. -If a keyword in an extended header record (or in a -o -option-argument) overrides or deletes a corresponding field in the -ustar header block, pax shall ignore the contents of that header +If a keyword in an extended header record (or in a -o +option-argument) overrides or deletes a corresponding field in the +ustar header block, pax shall ignore the contents of that header block field. -Unlike the ustar header block fields, NULs shall not delimit -<value>s; all characters within the <value> field shall be -considered data for the field. None of the length limitations of -the ustar header block fields in ustar Header Block shall apply to +Unlike the ustar header block fields, NULs shall not delimit +<value>s; all characters within the <value> field shall be +considered data for the field. None of the length limitations of +the ustar header block fields in ustar Header Block shall apply to the extended header records. pax Extended Header File Times -Time records shall be formatted as a decimal representation of the -time in seconds since the Epoch. If a period ( '.' ) decimal point -character is present, the digits to the right of the point shall -represent the units of a subsecond timing granularity. In read or -copy mode, the pax utility shall truncate the time of a file to -the greatest value that is not greater than the input header -file time. In write or copy mode, the pax utility shall output a -time exactly if it can be represented exactly as a decimal number, -and otherwise shall generate only enough digits so that the same -time shall be recovered if the file is extracted on a system whose +Time records shall be formatted as a decimal representation of the +time in seconds since the Epoch. If a period ( '.' ) decimal point +character is present, the digits to the right of the point shall +represent the units of a subsecond timing granularity. In read or +copy mode, the pax utility shall truncate the time of a file to +the greatest value that is not greater than the input header +file time. In write or copy mode, the pax utility shall output a +time exactly if it can be represented exactly as a decimal number, +and otherwise shall generate only enough digits so that the same +time shall be recovered if the file is extracted on a system whose underlying implementation supports the same time granularity. Example from Linux kernel archive tarball: |