shells: use (()) for math. not all support let. expr is external command

init.d/sysv/zapret

@@ -118,7 +118,7 @@ run_daemon()
 		PID=$(jobs -p %$JOBCT)
 		if [ -n "$PID" ]; then
 			echo $PID >$PIDFILE
-			JOBCT=`expr $JOBCT + 1`
+			JOBCT=$(($JOBCT+1))
 		else
 			echo could not start daemon $1 : $2 $3
 		fi

install_easy.sh

@@ -103,7 +103,7 @@ ask_list()
 	n=1
 	for m in $2; do
 		echo $n : $m
-		n=`expr $n + 1`
+		n=$(($n+1))
 	done
 	echo -n "your choice (default : $M_DEFAULT) : "
 	read m
@@ -424,7 +424,7 @@ openwrt_fw_section_find()
 		 	true
 	 		return
 		}
-		i=`expr $i + 1`
+		i=$(($i+1))
 	done
 	false
 	return

uninstall_easy.sh

@@ -135,7 +135,7 @@ openwrt_fw_section_find()
 		 	true
 	 		return
 		}
-		i=`expr $i + 1`
+		i=$(($i+1))
 	done
 	false
 	return