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## Appendix A Changes

This appendix lists some important user-visible changes between various versions of GNU `tar`. An up-to-date version of this document is available at the GNU `tar` documentation page.

Use of globbing patterns when listing and extracting.

  Previous versions of GNU tar assumed shell-style globbing when extracting from or listing an archive. For example:

      $ tar xf foo.tar '*.c'

  would extract all files whose names end in ‘`.c`’. This behavior was not documented and was incompatible with traditional tar implementations. Therefore, starting from version 1.15.91, GNU tar no longer uses globbing by default. For example, the above invocation is now interpreted as a request to extract from the archive the file named `*.c`.

  To facilitate transition to the new behavior for those users who got used to the previous incorrect one, `tar` will print a warning if it finds out that a requested member was not found in the archive and its name looks like a globbing pattern. For example:

      $ tar xf foo.tar  '*.c'
      tar: Pattern matching characters used in file names. Please,
      tar: use --wildcards to enable pattern matching, or --no-wildcards to
      tar: suppress this warning.
      tar: *.c: Not found in archive
      tar: Error exit delayed from previous errors

  To treat member names as globbing patterns, use the `--wildcards` option. If you want to tar to mimic the behavior of versions prior to 1.15.91, add this option to your `TAR_OPTIONS` variable.

  See wildcards, for the detailed discussion of the use of globbing patterns by GNU `tar`.

Use of short option `-o`.

  Earlier versions of GNU `tar` understood `-o` command line option as a synonym for `--old-archive`.

  GNU `tar` starting from version 1.13.90 understands this option as a synonym for `--no-same-owner`. This is compatible with UNIX98 `tar` implementations.

  However, to facilitate transition, `-o` option retains its old semantics when it is used with one of archive-creation commands. Users are encouraged to use `--format=oldgnu` instead.

  It is especially important, since versions of GNU Automake up to and including 1.8.4 invoke tar with this option to produce distribution tarballs. See v7, for the detailed discussion of this issue and its implications.

  See Changing Automake’s Behavior in GNU Automake, for a description on how to use various archive formats with `automake`.

  Future versions of GNU `tar` will understand `-o` only as a synonym for `--no-same-owner`.

Use of short option `-l`

  Earlier versions of GNU `tar` understood `-l` option as a synonym for `--one-file-system`. Since such usage contradicted to UNIX98 specification and harmed compatibility with other implementations, it was declared deprecated in version 1.14. However, to facilitate transition to its new semantics, it was supported by versions 1.15 and 1.15.90. The present use of `-l` as a short variant of `--check-links` was introduced in version 1.15.91.

Use of options `--portability` and `--old-archive`

  These options are deprecated. Please use `--format=v7` instead.

Use of option `--posix`

  This option is deprecated. Please use `--format=posix` instead.

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