TarTips

Fix A Broken Tar File

Estimate position of broken spot:

   $ tar tvf broken.tar | sed 's/  */ /g' | cut -d' ' -f3 | awk '{x+=$1;} END {print x;}'

In subdirectory, split file into workable chunks:
```
   $ split -b 20m ../broken.tar 
```

Use hex editor to search for broken spot:

   $ ghex2 xaa
     (find broken file path starting at 0x73B800 [offset1])
     (find next good file path starting at 0x7AE800 [offset2])

Help with hex-to-dec conversion:

   $ bc
   ibase=16
   73B800
   (answer is 7583744)
   7AE800
   (answer is 8054784)

Get total file length:
```
   $ ls -l xaa
   (size is 20971520) 
```
Take away good head part (offset1):
```
   $ head --bytes=7583744 < xaa > xaa1 
```

Take away good tail part (length - offset2):

   $ tail --bytes=12916736 < xaa > xaa2

Recombine head and tail, leaving out broken file:
```
   $ cat xaa1 xaa2 > xaa 
```
Remove working files:
```
   $ rm xaa1 xaa2 
```
Recombine all the parts:
```
   $ cat `ls -1` > ../fixed.tar 
```