MPE/iX Shell and Utilities Reference Manual, Vol 2

tar(1) MPE/iX Shell and Utilities tar(1)
–u updates an archive. This works like the –r form of the command, except that tar
adds files to the end of the tape archive only if they are not already there, or they
have been modified since the copy already in the archive. This option is not current-
ly implemented but will be included in a future release.
–x extracts files from an archive. tar extracts each named file to a file of the same
name. If you do not specify any files on the command line, tar extracts all files in
the archive. This extraction restores all file system attributes as controlled by other
options.
You must specify one of these basic options as the first character of an option string. You may
add other characters to the option string. Unlike other commands, you must give options as a
single string; for example, you might say –tv, but cannot separate them as in -t -v.You
may omit the leading dash – if you want. Other possible options in the option string are:
b sets the number of 512-byte blocks used for tape archive read/write operations to
blocksize. The blocksize argument must be specified, and blocksize may only be
specified when b is in the option string. When reading from the tape archive, tar
automatically determines the blocking factor by trying to read the largest legal block-
ing factor and using the actual number read to be the blocksize. For
UNIX compatibil-
ity, the largest valid blocksize is 20 blocks; in USTAR
mode, it is 60 blocks.
–C pathname
is an unusual option because it is specified in the middle of your file list. When tar
encounters a –C pathname option while archiving files, it changes the current direc-
tory (for tar only) to pathname and treats all following entries in your file list (in-
cluding another –C) as being relative to pathname.
f uses the file tapefile for the tape archive rather than the default. The tapefile argu-
ment must be specified, and tapefile may only be specified when f is in the option
string. The tapefile argument must precede the blocksize argument if both are
present. If tapefile is the character –, the standard input is used for reading and the
standard output is used for writing archives.
#s The default archive file name used by tar is /dev/mt/0m. This option is the least
general way to override this default. For a more general method, see the f option.
The file name generated by this option has the form /dev/mt/#s. The # may be
any digit between 0 and 7, inclusive, to select the tape unit. The density selector s
may be l(low), m(medium), or h(high).
l complains if all links are not resolved when adding files to the tape archive.
m does not restore a file’s modification time stamp when extracting it from an archive.
The default behavior is to restore the time stamp from information contained in the
archive.
Commands and Utilities 1-591