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Obscure sed extraction syntax

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# 1  
Old 01-20-2010
Obscure sed extraction syntax
Hi,

Could anyone clearly explain me the below sed construct in detail to get to know what it actually does?

Code:
sed 's/\([^ ]* *\)//4'

Code:
echo 'test;10;20' | sed 's/[^;]*;\([^;]*\)/\1/'

# 2  
Old 01-20-2010
The first is bit strange, as it is equivalent to:
Code:
sed 's/[^ ]* *//4'

It means delete the fourth word that is separated by spaces.

The second is also a bit strange as it is equivalent to:
Code:
sed 's/[^;]*;//'

It means delete anything upto and including the first ;
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