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Help with explanation of awk parameters

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# 1  
Old 09-27-2010
Help with explanation of awk parameters
Hello,

Would someone be able to tell me exactly how this command works please?

Code:
awk '!x[$0]++'

As usual any help much appreciated
# 2  
Old 09-27-2010
It eliminates matching lines by printing only lines which were not previously added to an array (x)
# 3  
Old 09-27-2010
Thanks Scott. I've been using it to remove blank lines from a file but I wondered what all the specific characters mean. IE:

!x
[$0]
++
# 4  
Old 09-27-2010
It will not only eliminate blank lines, but also nonempty duplicate lines. To delete blank lines this would be better:
Code:
awk '!/^$/'

# 5  
Old 09-27-2010
Hi.

It won't remove the first blank line - it only removes duplicate lines (blank or otherwise).

To remove all blank lines, the bartus11 solution is more suited.
# 6  
Old 09-27-2010
Or
Code:
awk NF

# 7  
Old 09-27-2010
Or
Code:
grep .

LOL
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