The usage -N to specify lines of context is no longer supported by diff:
$ rcsdiff -u10 foo
[...]
/usr/bin/diff: `-10' option is obsolete; use `-U 10'
$ rcsdiff -U 10 foo
rcsdiff: unknown option: -U
Trivial patch attached.
--bod
diff -Naur rcs-5.7.orig/src/rcsdiff.c rcs-5.7/src/rcsdiff.c
--- rcs-5.7.orig/src/rcsdiff.c 1995-06-16 16:19:24.000000000 +1000
+++ rcs-5.7/src/rcsdiff.c 2007-07-19 11:56:21.000000000 +1000
@@ -214,7 +214,7 @@
case '-': case 'D':
no_diff_means_no_output = false;
/* fall into */
- case 'C': case 'F': case 'I': case 'L': case 'W':
+ case 'C': case 'F': case 'I': case 'L': case 'U': case 'W':
#if DIFF_L
if (c == 'L' && ++file_labels == 2)
faterror("too many -L options");
