Grammar: 'effect' is a noun and 'affect' is a verb.

share/man/man4/inet.4

@@ -80,7 +80,7 @@ struct sockaddr_in {
 .Pp
 Sockets may be created with the local address
 .Dv INADDR_ANY
-to effect
+to affect
 .Dq wildcard
 matching on incoming messages.
 The address in a

share/man/man4/inet6.4

@@ -92,7 +92,7 @@ Sockets may be created with the local address
 which is equal to IPv6 address
 .Dv 0:0:0:0:0:0:0:0
 .Pc
-to effect
+to affect
 .Dq wildcard
 matching on incoming messages.
 .Pp

share/man/man4/netgraph.4

@@ -341,7 +341,7 @@ mode.
 The node is notified of a broken connection. The node may consider some hooks
 to be critical to operation and others to be expendable: the disconnection
 of one hook may be an acceptable event while for another it
-may effect a total shutdown for the node.
+may affect a total shutdown for the node.
 .It Shutdown of a node
 This method allows a node to clean up
 and to ensure that any actions that need to be performed

share/man/man4/termios.4

@@ -112,7 +112,7 @@ type a key (usually
 .Ql \&^Z )
 which generates the terminal stop signal
 .Pq Dv SIGTSTP
-and has the affect of stopping the entire job.
+and has the effect of stopping the entire job.
 The shell will notice that the job stopped, and will resume running after
 placing itself in the foreground.
 The shell also has commands for placing stopped jobs in the background,

share/man/man4/ukbd.4

@@ -130,8 +130,9 @@ option.
 options KBD_DISABLE_KEYMAP_LOADING
 .Ed
 .Pp
-Don't allow the user to change the keymap.  Note that this options
-also has effect on the AT keyboard driver `atkbd'.
+Don't allow the user to change the keymap.
+Note that these options also affect the AT keyboard driver
+.Xr atkbd 4 .
 .Sh FILES
 .Bl -tag -width /dev/kbd0 -compact
 .It Pa /dev/kbd*