How do I apply source code patches?

[Jarmo Paavilainen]

Hi,

I got a source code patch (from a email list) but I do not know how to apply
it?

It looks as follows:

--- diald-99/options.c  Thu Apr  1 17:42:14 1999
+++ newdiald-99/options.c       Sat Oct 16 11:11:41 1999
@@ -774,8 +774,8 @@
     int flag = 0;

     if (!ifsetup || !*ifsetup) {
-       if (!path_ifconfig || !*path_ifconfig)
-           flag = 1, mon_syslog(LOG_ERR, "No ifconfig program found.");
+       if ((!path_ifconfig || !*path_ifconfig) && (!path_ip || !*path_ip))

... and so on ...

// Jarmo