Line space problem facing

Shell Programming and Scripting
1

Hi,

I got a list of file that all got the same standard format.
Can anyone teach me how to put the space in all of them?!

Input file:
>nucleotide1
AAAAAAAAACCCGGG
>nucleotide2
GGGGGGCCCCCTTTTA
>nucleotide3
GGTACACCACACTCAC
>nucleotide4
TTTGGAGAGAGACCCC

desired output:
>nucleotide1
AAAAAAAAACCCGGG

>nucleotide2
GGGGGGCCCCCTTTTA

>nucleotide3
GGTACACCACACTCAC

>nucleotide4
TTTGGAGAGAGACCCC

Thanks a lot for all of your guide and suggestion :slight_smile:

2 
Input:
>nucleotide1
AAAAAAAAACCCGGG
>nucleotide2
GGGGGGCCCCCTTTTA
>nucleotide3
GGTACACCACACTCAC
>nucleotide4
TTTGGAGAGAGACCCC

$ sed 's/^>/\n>/g' filename

Output
>nucleotide1
AAAAAAAAACCCGGG

>nucleotide2
GGGGGGCCCCCTTTTA

>nucleotide3
GGTACACCACACTCAC

>nucleotide4
TTTGGAGAGAGACCCC
3

Thanks a lot skmdu,
It is worked now d :slight_smile:
I very appreciate for your help ^^

4 
sed -n '/>/!{p;}
        />/{
        1{p;}
        1!{x;p;x;p;}
        }' a.txt
5

can't work?!