adding symbol to newlines with out replacing them

Guyz

I have been using tr command to replace symbol.
I would like to add a symbol to all newlines in a textfile with out replacing them

input
\n (i mean new line)
a
\n
b
\n
c

output
>
a
>
b
>
c

---------- Post updated at 12:45 AM ---------- Previous update was at 12:40 AM ----------

I found it

Never mind

$ cat fasta3.txt | sed 's/$/\>/g' >fasta4.txt