19.8 Problems with Verbose tar

I've heard of one tar version with a v (verbose) option that writes the verbose information to its standard output, rather than standard error. If your tar does that, be sure not to use v when you're using tar to write to a pipeline. For example, the command that follows would be a disaster if your version of tar has this bug:

% 

tar cvf - *.txt | gzip > archive.tar.gz

The filenames would appear in standard output, along with the tar archive itself. The result would be a gzip ped archive that couldn't be extracted. (You'd probably get a "checksum error" from tar , or something similar, if you tried.)

You can test for this problem by typing:

% 

tar cvf -

 

somefile

 

> /dev/null

   
tar without
 
v
 
bug

a 

somefile

 23 blocks, 44567 characters

That redirects standard output to /dev/null ( 13.14 ) . If you don't see any verbose output, your tar has the bug.