[clug] 'dd' command detecting EOF: an example script

Peter Barker pbarker at barker.dropbear.id.au
Wed May 15 08:02:51 UTC 2019

On Wed, 15 May 2019, Steve Jenkin wrote:

> Peter,
> thanks very much for that - hadn’t caught up with GNU split ‘chunking’ to a command.
> Doesn’t write to STDOUT, so extra work needed to insert into a pipeline.

You know, that's the way I initially read it too.  Turns out $FILE is the 
*output* filename!

But check out "split" here: 


     With this option, rather than simply writing to each output file, 
write through a pipe to the specified shell command for each output file. 
command should use the $FILE environment variable, which is set to a 
different output file name for each invocation of the command. For 
example, imagine that you have a 1TiB compressed file that, if 
uncompressed, would be too large to reside on disk, yet you must split it 
into individually-compressed pieces of a more manageable size. To do that, 
you might run this command:

     xz -dc BIG.xz | split -b200G --filter='xz > $FILE.xz' - big-

> steve

Peter Barker                          |   Programmer,Sysadmin,Geek.
pbarker at barker.dropbear.id.au	      |   You need a bigger hammer.
:: in what circumstances would you want reverse thrust for takeoff? --tridge

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