Next: 4.5.3 Putting them together Up: 4.5 Archiving and Compressing Previous: 4.5.1 Using tar

## 4.5.2 gzip and compress

Unlike archiving programs for MS-DOS, `tar` does not automatically compress files as it archives them. Therefore, if you are archiving two 1-megabyte files, the resulting tar file will be two megabytes in size. The `gzip` command may be used to compress a file (the file to compress need not be a tar file). The command

`# gzip -9 backup.tar`

will compress `backup.tar` and leave you with `backup.tar.gz`, the compressed version of the file. The `-9` switch tells `gzip` to use the highest compression factor.

The `gunzip` command may be used to uncompress a gzipped file. Equivalently, you may use ```gzip -d`''.

`gzip` is a relatively new tool in the UNIX community. For many years, the `compress` command was used instead. However, because of several factors, `compress` is being phased out.

`compress`ed files end in the extension `.Z`. For example, `backup.tar.Z` is the compressed version of `backup.tar`, while `backup.tar.gz` is the gzipped version. The `uncompress` command is used to expand a `compress`ed file; `gunzip` knows how to handle `compress`ed files as well.

Next: 4.5.3 Putting them together Up: 4.5 Archiving and Compressing Previous: 4.5.1 Using tar