retrieve every 4th line from a file


 
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# 1  
Old 03-27-2009
Question retrieve every 4th line from a file

Hello,

I want to retrieve 2, 6, 10, 14...... (each 4 lines apart) from a file that looks like the sample below. In other words, I want only lines corresponding to the Xs.

Header1_a
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Header1_b
yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
Header2_a
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Header2_b
yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
Header3_a
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Header3_b
yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
.....
.....



Thanks for your help!
-G
# 2  
Old 03-27-2009
This sed command will start at line 2 and then print every 4th line after that from the input file
Code:
sed -n '2~4p' input_file

# 3  
Old 03-27-2009
Thanks ldapswandog!
-G
 
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