Commands for the transfer of files across filesystems and machines

A tar to and from a local tape drive
```
     nice tar cvphf /dev/rst0 ./public 
     nice tar tvf   /dev/rst0
     nice tar xvpf  /dev/rst0 
     
```
The c flag creates the tar, the x file extracts from the tar.
The t flag reads the table of contents from the tar.
The p flag preserves the file permission settings.
The h flag follows links (undesirable when backing up a device, but desireable when backing up a directorystructure.

An efficient copy command even across file systems.

     cd fromdir; tar cf - . | (cd  todir;  tar xfBp -)

Across the Ethernet to a tape drive
How to archive files from the local machine (example) to a tape on a remote system (host):
```
     example% tar cvfb  -  20 filenames | rsh host dd of=/dev/rmt0  obs=20b 
     
```
In the example above, we are creating a tarfile with the c key letter, asking for verbose output from tar with the v option, specifying the name of the output tarfile using the f option (the standard output is where the tarfile appears, as indicated by the `-' sign), and specifying the blocksize (20) with the b option. If you want to change the block- size, you must change the blocksize arguments both on the tar command and on the dd command.
Here is a real life example from Taal:
```
     tar cvfb  -  20 avo_cdps.HH avo_cdps.sepdata | rsh oas dd of=/dev/rst1 obs=20b
     
```
Next time try this:
```
     dump 0dsbfu 54000 6000 126 - /dev/sd0a | rsh oas dd of=/dev/rst1 obs=20b
     
```
dump 0=dump all, d=54000 density tape 8mm, s=6000 size length of tape, b=126 blocksize (block=126byte), f=- file is pipeline u=/dev/sd0a unit to dump
From a tape drive on a remote system to the local system
```
      example% rsh -n host  dd  if=/dev/rmt0   bs=20b  |  tar xvBfb  - 20 filenames
      
```
In the example above, we are extracting from the tarfile with the x key letter, asking for verbose output from tar with the v option, telling tar it is reading from a pipe with the B option, specifying the name of the input tarfile using the f option (the standard input is where the tarfile appears, as indicated by the `-' sign), and specifying the blocksize (20) with the b option.
Real Life example on alpamayo:
```
      rsh -n oas dd  if=/dev/rst1   bs=20b  |  tar xvBfb  - 20 avo_cdps.HH avo_cdps.sepdata
      
```