Tar

Internal

• Linux

Overview

tar -cvf <archive-name> <files>

tar -xf <archive-name>

It is important that <archive-name> follows immediately after -f.

Handling Symbolic Links

https://www.gnu.org/software/tar/manual/html_node/dereference.html

By default, tar handles archiving symbolic links by writing a block to the archive with the name of the target of the link, thus preserving the symbolic link. However, if the -h|--dereference option is used when creating the archive, tar archives the content of the file the symbolic link points to instead of the symbolic link information.

To create a portable archive aimed at systems that do not support symbolic links, use -h|--dereference.

Handling Hard Links

https://www.gnu.org/software/tar/manual/html_node/hard-links.html

Options

Archival

When tar is executed as root, the file permissions and owner are preserved.

-p

Preserve permissions, default when the root executes the command.

-s

Preserve order (same order). Sort names to extract to match archive.

-z

Compress, produce a tgz.archive.

-C

Source directory when creating the archive. Target directory when extracting the archive.

For

/
└── home
      └── someuser
             └── A
                 ├── X
                 ├── Y
                 └── Z
                     └── somefile.txt

tar -cvf test.tar -C /home/someuser/A Z

will produce a test.tar that contains:

 Z
 └── somefile.txt

-h|--dereference

See Handling Symbolic Links above.

Archive

Archive maintaining the user IDs and file permissions:

tar -cvspf .../archive.tar *

Note that the name of the archive file to be created must immediately follow -f, without any interceding parameters.

To also gzip:

tar cfv - ./mydir | gzip > mydir.tgz

Exclude Specific Files from Archive

tar cf <file-name.tar> --exclude <pattern>  <dir>

Do not process files or directories that match the specified pattern. Note that exclusions take precedence over patterns or filenames specified on the command line.

Example:

tar cfv module.tar --exclude */Jenkinsfile --exclude */jenkins module/

Restoration

Restore preserving the user ID and file permissions (if done as root, the behavior is implicit):

tar -xvspf .../archive.tar

Extract a Specified File

tar -xf archive.tar some/specific/file.txt

gunzip < ... | tar xfv - some/specific/file.txt

Troubleshooting

With some versions of tar I get this:

tar -xfz /.../a.tar.gz -C /usr/lib/jvm/
tar: z: Cannot open: No such file or directory

The problem goes away if I don't use "-".