Tar: Difference between revisions

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* [[Linux#Commands|Linux]]
* [[Linux#Commands|Linux]]
=Overview=
<syntaxhighlight lang='bash'>
tar -cvf <archive-name> <files>
</syntaxhighlight>
<syntaxhighlight lang='bash'>
tar -xf <archive-name>
</syntaxhighlight>
It is important that <archive-name> follows immediately after -f.
=Handling Symbolic Links=
{{External|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.7C--dereference|-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.7C--dereference|-h|--dereference]].
=Handling Hard Links=
{{External|https://www.gnu.org/software/tar/manual/html_node/hard-links.html}}


=Options=
=Options=
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Preserve order (same order). Sort names to extract to match archive.
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
<syntaxhighlight lang='text'>
/
└── home
      └── someuser
            └── A
                ├── X
                ├── Y
                └── Z
                    └── somefile.txt
</syntaxhighlight>
<syntaxhighlight lang='bash'>
tar -cvf test.tar -C /home/someuser/A Z
</syntaxhighlight>
will produce a test.tar that contains:
<syntaxhighlight lang='text'>
Z
└── somefile.txt
</syntaxhighlight>
===-h|--dereference===
See [[#Handling_Symbolic_Links|Handling Symbolic Links]] above.


=Archive=
=Archive=
Line 24: Line 78:


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


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


  tar -xvspf .../archive.tar
  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 <code>tar</code> I get this:
<syntaxhighlight lang='text'>
tar -xfz /.../a.tar.gz -C /usr/lib/jvm/
tar: z: Cannot open: No such file or directory
</syntaxhighlight>
The problem goes away if I don't use "-".

Latest revision as of 00:04, 26 June 2021

Internal

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 "-".