Perl - " > ", , :
use Modern::Perl;
local $/ = '>';
do { s/\n/\t/; print }
for <DATA>;
__DATA__
>00000_x1688514
TGCTTGGACTACATATGGTTGAGGGTTGTA
>00001_x238968
TGCTTGGACTACATATTGTTGAGGGTTGTA
:
>00000_x1688514 TGCTTGGACTACATATGGTTGAGGGTTGTA
>00001_x238968 TGCTTGGACTACATATTGTTGAGGGTTGTA
:
use Modern::Perl;
use autodie;
open my $inFile, '<', 'inFile.txt';
open my $outFile, '>', 'outFile.txt';
local $/ = '>';
do { s/\n/\t/; print $outFile $_ }
for <$inFile>;
close $inFile;
close $outFile;
, !