[bonsai@mainserver tests]$ cat file
Foo
[bonsai@mainserver tests]$ ls -i file
589826 file
[bonsai@mainserver tests]$ ed file <<< $'1s/F/f\nw' &>/dev/null
[bonsai@mainserver tests]$ ls -i file
589826 file
[bonsai@mainserver tests]$ cat file
foo
[bonsai@mainserver tests]$