In Unix, what is tar, and how do I use it?
In Unix, the name of the
tar command is short for tape archiving, the storing of entire file systems onto magnetic tape, which is one use for the command. However, a more common use for
tar is to simply combine a few files into a single file, for easy storage and distribution.
To combine multiple files and/or directories into a single file, use the following command:
tar -cvf file.tar inputfile1 inputfile2
inputfile2 with the files and/or directories you want to combine. You can use any name in place of
file.tar, though you should keep the
.tar extension. If you don't use the
tar assumes you really do want to create a tape archive instead of joining up a number of files. The
v option tells
tar to be verbose, which reports all files as they are added.
To separate an archive created by
tar into separate files, at the shell prompt, enter:
tar -xvf file.tar
Compressing and uncompressing tar files
Many modern Unix systems, such as Linux, use GNU
tar, a version of
tar produced by the Free Software Foundation. If your system uses GNU
tar, you can easily use
gzip (the GNU file compression program) in conjunction with
tar to create compressed archives. To do this, enter:
tar -cvzf file.tar.gz inputfile1 inputfile2
z option tells
tar to zip the archive as it is created. To unzip such a zipped tar file, enter:
tar -xvzf file.tar.gz
Alternatively, if your system does not use GNU
tar, but nonetheless does have
gzip, you can still create a compressed tar file, via the following command:
tar -cvf - inputfile1 inputfile2 | gzip > file.tar.gz
gzipisn't available on your system, use the Unix
compresscommand instead. In the example above, replace
compressand change the
compresscommand specifically looks for an uppercase Z). You can use other compression programs in this way as well. Just be sure to use the appropriate extension for the compressed file, so you can identify which program to use to decompress the file later.
If you are not using GNU
tar, to separate a tar archive that was compressed by
gunzip -c file.tar.gz | tar -xvf -
Similarly, to separate a tar archive compressed with the Unix
compress command, replace
Lastly, the extensions
.tar.gz are equivalent; they both signify a tar file zipped with
Keep the following in mind when using the
- The order of the options sometimes matters. Some versions of
tarrequire that the
foption be immediately followed by a space and the name of the
.tarfile being created or extracted.
- Some versions require a single dash before the option string (e.g.,
tar does not have either of these limitations.
tar command has many additional command options available. For more information, consult the manual
page. At the shell prompt, enter:
tar comes with additional documentation, including a tutorial, accessible through the GNU Info interface. You can access this documentation by entering:
Within the Info interface, press
? (the question mark) for a list of commands.
At Indiana University, for personal or departmental Linux or Unix systems support, see At IU, how do I get support for Linux or Unix?
This is document acfi in the Knowledge Base.
Last modified on 2016-12-06 11:11:00.
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