Essential System Administration, 3rd Edition

Restoring Files from Backups

All of the backup facilities described in the previous sections have corresponding file restoration facilities. We’ll look at each of them in turn in this section.

Restores from tar and cpio Archives

Individual files or entire subtrees can be restored easily from tar and cpio archives. For example, the following pairs of commands restore the file /home/chavez/freeway/quake95.data and user harvey’s home directory (respectively) from an archive made of /home located on the tape in the default tape drive (here, we use /dev/rmt0 for as the example location):

$ tar -xp /home/chavez/freeway/quake95.data
$ cpio -im '*quake95.data' < /dev/rmt0
$ tar -xp /home/harvey
$ cpio -imd '/home/harvey*' < /dev/rmt0

The -p option to tar and -m option to cpio ensure that all file attributes are restored along with the file. cpio’s -d option creates subdirectories as necessary when restoring a directory subtree (tar does so by default).^[18]

Restores with pax are similar. For example, the first of the following commands lists the files on the tape in drive 0, and the remaining commands extract various files from it:

$ pax -f /dev/rmt0 -v               
               -v
                
               gives a more detailed/verbose listing. 
$ pax -r '/h95/*.exe'               
               Select files via a regular expression. 
$ pax -r /home/chavez               
               Restore chavez's home directory. 
$ pax -r -f my_archive -c '*.o'     
               Restore everything except object files.
# pax -r -pe -f /dev/rmt0           
               Restore files incl. owner, mode & mod. time. 

pax’s coolest feature has to be its ...