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How to delete lines starting with specific string?

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# 1  
Old 07-30-2014
How to delete lines starting with specific string?
Dear all,

I would like to delete even lines starting with "N" together with their respective titles which are actually odd lines.

Below is the example of input file. I would like to remove line 8 and 12 together with its title line, i.e., line 7 and 11, respectively.
Code:
>M01596:22:000000000-A7YH7:1:1101:16615:1070 2:N:0:1
CAAGGTATTATAAGCCGTACAGGTGCCGTCGCGTACTCGCGTGAAACTCCTATCCTCTCCTGCTCGGCATTCGAATTCAGGTCGTGCT
>M01596:22:000000000-A7YH7:1:1101:19605:1070 2:N:0:1
TTCAGAGTAACACCGGAAAGCGTTACCGCTAATTGTTGAGCACGATGCCAATCACGGCGATGTTCGAATTATTGTTGTGCTCGCTACA
>M01596:22:000000000-A7YH7:1:1101:9956:1070 2:N:0:1
GCCGGGCAATAATGTTTATGTTGGTTTCATGGTTTGGTCTAACTTTACCGCTACTAAATGCCGCGGATTGGTTTCGCTGAATCAGGTT
>M01596:22:000000000-A7YH7:1:1101:21195:1071 2:N:0:1
NTCCTCAAGGCGTCAGTATTGTTGAAGTTGTGTCCATCAGGGAGGTGACAATGAATTTCTGCTGTGCTCGCTACAGACTCGGACAGATC
>M01596:22:000000000-A7YH7:1:1101:12710:1082 2:N:0:1
TCAAATCCGGCGTCAACCATACCAGCAGAGGAAGCATCAGCACCAGCACGCTCCCAAGCATTAAGCTCAGGAAATGCAGCAGCAAGAT
>M01596:22:000000000-A7YH7:1:1101:21487:1088 2:N:0:1
NNGAGAGGCCGGGGCATTTTCCGCTGCGGTTGGGACGGGAGAGGCCAGGGGCGTGCCATCGAGCACTACTGGAGAAAAATGATCTTTGCT
>M01596:22:000000000-A7YH7:1:1101:11107:1088 2:N:0:1
TCGCTGCGTTGAGGCTTGCGTTTATGGTACGCTGGACTTTGTAGGATACCCTCGCTTTCCTGCTCCTGTTGAGTTTATTGCTGCCGTC


The output file i would like to have is as follows:
Code:
>M01596:22:000000000-A7YH7:1:1101:16615:1070 2:N:0:1
CAAGGTATTATAAGCCGTACAGGTGCCGTCGCGTACTCGCGTGAAACTCCTATCCTCTCCTGCTCGGCATTCGAATTCAGGTCGTGCT
>M01596:22:000000000-A7YH7:1:1101:19605:1070 2:N:0:1
TTCAGAGTAACACCGGAAAGCGTTACCGCTAATTGTTGAGCACGATGCCAATCACGGCGATGTTCGAATTATTGTTGTGCTCGCTACA
>M01596:22:000000000-A7YH7:1:1101:9956:1070 2:N:0:1
GCCGGGCAATAATGTTTATGTTGGTTTCATGGTTTGGTCTAACTTTACCGCTACTAAATGCCGCGGATTGGTTTCGCTGAATCAGGTT
>M01596:22:000000000-A7YH7:1:1101:12710:1082 2:N:0:1
TCAAATCCGGCGTCAACCATACCAGCAGAGGAAGCATCAGCACCAGCACGCTCCCAAGCATTAAGCTCAGGAAATGCAGCAGCAAGAT
>M01596:22:000000000-A7YH7:1:1101:11107:1088 2:N:0:1
TCGCTGCGTTGAGGCTTGCGTTTATGGTACGCTGGACTTTGTAGGATACCCTCGCTTTCCTGCTCCTGTTGAGTTTATTGCTGCCGTC

Thanks in advance.
# 2  
Old 07-30-2014
IMHO, awk seems to be the candidate for this job. Use awk to read the title and the next line (using getline function). If the 2nd line (fetched using getline) doesn't start with N, print title and the next line, else skip to the next title.

Let us know what you have tried.
This User Gave Thanks to balajesuri For This Post:
huiyee1
# 3  
Old 07-30-2014
I have found the solution.

Code:
sed "N;/\nN/d" input.txt

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