udhcpc: tweak math shell style with the metric var

Some shells (like dash) are lame and omit the POSIX increment/decrement
feature (because it is listed as optional).  Tweak the shell script to
work in all POSIX variants.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

diff --git a/examples/udhcp/simple.script b/examples/udhcp/simple.script
index d42f2d3..0397e50 100755 (executable)
--- a/examples/udhcp/simple.script
+++ b/examples/udhcp/simple.script
@@ -29,7 +29,8 @@ case "$1" in
                        metric=0
                        for i in $router ; do
                                echo "Adding router $i"
-                               route add default gw $i dev $interface metric $((metric++))
+                               route add default gw $i dev $interface metric $metric
+                               : $(( metric += 1 ))
                        done
                fi