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Old 01-09-2008, 04:34 PM   #1
wangxinmco
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Registered: Dec 2007
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how to delete two adjecent lines in a text file


hello, experts,
I need to delete the lines containing letter "a" and the next line together from a tect file.
I found the two lines with
fgrep a -A 1 filename
But I do not know how to delete them.

Please help me,

Thank you in advance,
 
Old 01-09-2008, 08:39 PM   #2
ghostdog74
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Code:
awk '/a/{getline;next}1' file
 
Old 01-10-2008, 02:35 PM   #3
osor
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Quote:
Originally Posted by ghostdog74 View Post
Code:
awk '/a/{getline;next}1' file
The problem with this sort of approach is that it removes two lines without applying the pattern match to next itself. This might cause trouble when you have an even number of consecutive lines containing the character a in your file.

For example, if file is the following:
Code:
a
ba
c
d
Your filter will result in the following output:
Code:
$ awk '/a/{getline;next}1' file
c
d
But the desired output would be:
Code:
d
It is unclear (to me anyway) if the OP is affected by this problem.
 
Old 01-10-2008, 03:23 PM   #4
bigrigdriver
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sed -e '/a/,2D' <filename>
will delete all lines with 'a' in them, but the first instance will also delete the following line.

Last edited by bigrigdriver; 01-10-2008 at 03:31 PM.
 
  


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