i do some like this ...

echo "" >> file1 puts the new line at the end of the file.



$ cat abcd.txt
abcde
abdcrewuroewr
abababbaaba
abbabbaba$ echo "" >> abcd.txt
$ cat abcd.txt
abcde
abdcrewuroewr
abababbaaba
abbabbaba
$ sed '${$a \ }' abcd.txt
$ sed 's/a/b/g/ abcd.txt
>
$ sed 's/a/b/g' abcd.txt
bbcde
bbdcrewuroewr
bbbbbbbbbbb
bbbbbbbbb
$