The command 'e' when entered without a filename is supposed to re-read the current file and discard any changes. However, in GNU ed, it quits instead. The ed implementation supplied with Mac OS X Leopard works as expected. See the example below.
GNU ed:
$ ed
H
P
*f file
file
*a
some text
.
*w
10
*e
10
*a
more text
.
*e
?
Warning: file modified
*e
$
Mac OS X Leopard:
$ ed
H
P
*f file
file
*a
some text
.
*w
10
*e
10
*a
more text
.
*e
?
warning: file modified
*e
10
*1,$p
some text
*q
$