ptar(C)

ptar -- process tape archives

Syntax

ptar -c [ bLfvw ] device block filename ...

ptar -r [ bLvw ] device block [ filename ... ]

ptar -t [ fv ] device

ptar -u [ bLvw ] device block

ptar -x [ flmovw ] device [ filename ... ]

Description

The ptar command reads and writes archive files which conform to the Archive/Interchange File Format specified in IEEE Std. 1003.1-1988.

Options

The following options are available:

-c: Creates a new archive; writing begins at the beginning of the archive, instead of after the last file.
-r: Writes named files to the end of the archive.
-t: Lists the names of all of the files in the archive.
-u: Causes named files to be added to the archive if they are not already there, or have been modified since last written into the archive. This implies the -r option.
-x: Extracts named files from the archive. If a named file matches a directory whose contents had been written onto the archive, that directory is recursively extracted.

If a named file in the archive does not exist on the system, the file is created with the same mode as the one on the archive, unless the process does not have the appropriate privileges. In this case the access permissions are set in the same fashion that creat would have set them when given the ``mode'' argument, matching the file permissions supplied by the ``mode'' field of the ptar format. The set-user-id and get-group-id modes are not set unless the user has the appropriate privileges.

If the files exist, their modes are not changed except as described above. The owner, group and modification time are restored if possible. If no filename argument is given, the entire contents of the archive are extracted. Note that if several files with the same name are in the archive, the last one will overwrite all earlier ones.

-b: Causes ptar to use the next argument on the command line as the blocking factor for tape records. The default is 1; the maximum is 20. This option should only be used with raw magnetic tape archives. Normally, the block size is determined automatically when reading tapes.
-f: Causes ptar to use the next argument on the command line as the name of the archive instead of the default, which is usually a tape drive. If ``-'' is specified as a filename, ptar writes to the standard output or reads from the standard input, whichever is appropriate for the options given. Thus, ptar can be used as the head or tail of a pipeline.
-l: Tells ptar to report if it cannot resolve all of the links to the files being archived. If -l is not specified, no error messages are written to the standard output. This modifier is only valid with the -c, -r and -u options.
-L: Causes ptar to follow symbolic links.
-m: Tells ptar not to restore the modification times. The modification time of the file will be the time of extraction. This modifier is invalid with the -t option.
-o: Causes extracted files to take on the user and group identifier of the user running the program rather than those on the archive. This modifier is only valid with the -x option.
-v: Causes ptar to operate verbosely. Usually, ptar does its work silently, but the -v modifier causes it to print the name of each file it processes, preceded by the option letter. With the -t option, -v gives more information about the archive entries than just the name.
-w: Causes ptar to print the action to be taken, followed by the name of the file, and then wait for the user's confirmation. If a word beginning with y is given, the action is performed. Any other input means ``no''. This modifier is invalid with the -t option.

Files

/dev/tty: used to prompt the user for information when the -i or -y options are specified

Standards conformance

ptar is not part of any currently supported standard; it was developed by Mark H. Colburn of NAPS International, 117 Mackubin Street, Suite 1, St. Paul, MN 55102 (mark@jhereg.MN.ORG), as sponsored by The USENIX Association for public distribution, and is used with permission.