Unix Information - Backing Up
by D.W. Hyatt
Backing Up Files
Since catestrophic errors happen within our computer lab from time to time,
we recommend all users to save important files to disk occasionally.
Tape Archive - tar
The tar command is frequently used to save entire directory
structures into an archive. To create a backup file of a firectory
type tar followed by argument c for create, v
for verbose so that we can see what it is saving, and f to
indicate that the output is going to a file. After that, the user also
adds the name of the backup file followed by the directory to be
saved. Here is the full command.
-
tar -cvf backup.tar dir-name
To untar, just type tar with the argument x instead
of c for extract.
-
tar -xvf backup.tar
It will create the directory as well as any subdirectories in the restore
process.
Compressing Files - gzip
To compress a file, the gzip compression utility is often a useful
tool. The following will compress the backup file produced above to
a compressed version. The result will be a file called backup.tar.gzshowing that it has been compressed with the gzip utility.
-
gzip backup.tar
To uncompress, just type gunzip followed by the file name.
-
gunzip backup.tar.gz
Since it is often true that people wish to archive directories and
compress the resultant files to save space, the tar command with
the z argument also compresses using gzip, accomplishing
both tasks. The following creates a compressed archive file
of the specified directory.
-
tar -cvfz backup.tar.gz dir-name
To uncompress, just type
-
tar -xvfz backup.tar.gz
Saving to a Floppy
Files can be copied directly to a floppy disk on the A-Drive by using the
mcopy command.
-
mcopy backup.tar.gz a:
Howver, it is also possible to use the tar command to save directy
to the A-Drive, using the following command. This command also uses the
M argument in case the file is too big for one disk and must
be spread out over Multiple Volumes, or several floppy disks.
-
tar -cvfzM /dev/fd0/backup.tar.gz dir-name
To uncompress, just use the extract version. Just be sure to put
the disks into the A-Drive in the proper order.
-
tar -xvfzM /dev/fd0/backup.tar.gz