Linux System Administrators' Guide 0.6

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Restoring files with `tar`

The -extract (-x) option for tar extracts files:

# tar -extract -same-permissions -verbose -file /dev/fd0H1440 usr/src/ usr/src/linux usr/src/linux-1.2.10-includes/ usr/src/linux-1.2.10-includes/include/ usr/src/linux-1.2.10-includes/include/linux/ usr/src/linux-1.2.10-includes/include/linux/hdreg.h usr/src/linux-1.2.10-includes/include/linux/kernel.h ... #

You also extract only specific files or directories (which includes all their files and subdirectories) by naming on the command line:

# tar xpvf /dev/fd0H1440 usr/src/linux-1.2.10-includes/include/linux/hdreg.h usr/src/linux-1.2.10-includes/include/linux/hdreg.h #

Use the -list (-t) option, if you just want to see what files are on a backup volume:

# tar -list -file /dev/fd0H1440 usr/src/ usr/src/linux usr/src/linux-1.2.10-includes/ usr/src/linux-1.2.10-includes/include/ usr/src/linux-1.2.10-includes/include/linux/ usr/src/linux-1.2.10-includes/include/linux/hdreg.h usr/src/linux-1.2.10-includes/include/linux/kernel.h ... #

Note that tar always reads the backup volume sequentially, so for large volumes it is rather slow. It is not possible, however, to use random access database techniques when using a tape drive or some other sequential medium.

tar doesn't handle deleted files properly. If you need to restore a filesystem from a full and an incremental backup, and you have deleted a file between the two backups, it will exist again after you have done the restore. This can be a big problem, if the file has sensitive data that should no longer be available.

Lars Wirzenius
Sat Nov 15 02:32:11 EET 1997