Shell Programming and Scripting

Hi. I am very new to the unix world, although not to computers in general (i'm a DBA). We have some procedure here for backup files from the filesystem to tape, on which they chose cpio to back it up. What they do is similar to this:

ls /dirname/ | cpio -ov -O/dev/ntape/tape0

But since files have grew to more than 10GB in size on /dirname/ ( we use 8GB tapes ), there seem to be a problem, allthough I haven't determined whether or not is cpio causing it. So, my question to you all is, will cpio span tapes files (like tar for example) in case there's no sufficient storage to backup all files ?

Thank you very much.

cpio -- Copy File Archives In and Out

cpio stands for "copy in, copy out" and is used to copy data from one location to another. There are several advantages to using cpio over other

UNIX utilities:

1) cpio can back up and restore individual files, not just whole file systems.
2) File header information on files created by cpio is smaller, resulting in smaller-sized backups.
3) Unlike tar, which is limited to a single tape device, cpio can span multiple tapes.

cpio operates in three modes: copy-out ( cpio -o), copy-in ( cpio -i), and pass mode ( cpio -p), which is used to copy files from one location to another on disk and not tape. The following section lists several commonly used options.

cpio Command Options

These options apply to copy-out and copy-in modes, unless otherwise noted.

-c: Write header information in ASCII format, for portability.
-d: Create as many directories as needed.
-v: Verbose (report the names of the files as they are processed).
-V: Same as the preceding, except a "." is printed for each file copied.
-u: Use for an unconditional copy; old files will not replace newer versions.
-m: Retain the previous file modification time. This option will not work on directories being copied.


To copy a directory and its subdirectories to tape, use the following example:

% ls -R | cpio -oVc > /dev/rmt/0

The previous example will copy the directory that you are currently in -- along with all subdirectories within it -- to a tape device located at /dev/rmt/0. The -o specifies that we are in copy-out mode. The -V option is for verbose and will display dots as a progress indicator. The -c option create an ASCII header file.

To copy from tape back to a directory, use the following example:

% cpio -icvD < /dev/rmt/0

In the preceding example, our command will use several options to restore the contents of data on the tape. The -i option puts us in copy-in mode. The -d option creates all the directories needed as it copies the data back.

Backing Up Files With cpio (Copy-Out Mode)

There are several ways to back up files with cpio. I'll cover two of them here in the article.


% cpio -ov list > /dev/rmt/0This command reads from the file "list" and copies them over to a tape device.


% cpio -o /dev/rmt/0This command will allow you to specify files to be backed up. After you are finished entering file names, hit Ctrl+D to execute the command. Here's an example:

% cpio -o > /dev/rmt/0
filename.txt
file1name.txt

Restoring Files With cpio (Copy-In Mode)

The restore process with cpio is similar to backing up files. Instead of the -o for copy-out, we use the -i mode to copy back in from tape.


% cpio -icvum < /dev/rmt/0This example utilizes similar options used earlier, as well as the -m option, which will preserve file modification times.

Use the following example to view a list of contents on the tape archive:
% cpio -ict < /dev/rmt/0Pass Mode

Pass mode can be used to copy directories on a disk device. It will not work against a tape. cpio is preferred over cp when copying files and directories because it preserves ownership and modification times.

The following example copies all files and directories to a directory called bkup:

% ls * | cpio -pdumv bkup

Allright, I'm sorry to said that I already read that :-S .. the problem might be another then. It is strange, but I remember doing a tar the other day when it asked for another tape when it was fill. Could that be possible ?