Counting a specific consecutive character with its occurrence position and length I have a sequence file and want to count consecutive character "N", with the tandem's position of occurrence and its length. Say I have a file named mySequence.fasta like this:

&gt;sequence-1 
ATCGCTAGCATNNNNNNNNNNNNNNCTAGCATCATGCNNNNNNATACGCATCACANNNNNNNNNCgcatATCAC


and anticipated output should be like this:

Position 12 N 15
Position 38 N 6
Position 56 N 9


Kindly help me to solve this by awk or sed providing my file name mySequence.fasta
I couldn't come up with a one liner but have a two liner instead...

To get the start positions of the N repeat:

grep N mySeq.fasta | grep -b -o N | awk -F: '{print $1}' |awk '$1!=p+1{print $1}{p=$1}'
12
38
56


To get the length of the repeats:

grep N mySeq.fasta | awk -F '[^N]+' '{for (i=1; i&lt;=NF; i++) if ($i != "") print length($i)}' 
14
6
9


With thanks to stack overflow.