I have fasta file (modelfasta.fasta) like this:>seq1AAAAAAAAAAAAAAAGGGGGGGGGGG>seq2TTTTTTTTTTTTTTTCCCCCCCI am expecting output like this:>header>seq1AAAAAAAAAAAAAAAGGGGGGGGGGG>header>seq2TTTTTTTTTTTTTTTCCCCCCCI tried with sed and awk command with fasta  example file (modelfasta.fasta) but getting output in this way awk '{printf $0}' modelfasta.fasta >seq1AAAAAAAAAAAAAAAGGGGGGGGGGG>seq2TTTTTTTTTTTTTTTCCCCCCCit removes newline just after header too and merges sequences with the headerthe same result found with sed sed ':a;N;$!ba;s/\n//g' modelfasta.fasta>seq1AAAAAAAAAAAAAAAGGGGGGGGGGG>seq2TTTTTTTTTTTTTTTCCCCCCCI want all the new lines removed except header's one, please help 
how to remove newline characters in fasta sequence
linux;shell script;awk;sed;newlines