rename fastq file headers using sed command

Question

I am trying to rename the fastq header and add "/1" at the end of fastq header using sed commmand. Here is my code:

sed i '1~4 s/$/\\1/g' seq/*_1.fq

But no change has been made. Does someone know how to solve this? Thanks!

Answer 1

This will add /1 to line n * 4 + 1 where n >= 0 for the files matching the glob seq/*_1.fq:

sed -i '1~4s/$/\/1/' seq/*_1.fq

You did not provide any input to here is what I used:

a
b
c
d
e
f

and the result was:

a/1
b
c
d
e/1
f