ci: various build updates before adding Azure pipelines

ci/travis/before_install_darwin

@@ -1,4 +1,4 @@
-#!/bin/sh -xe
+#!/bin/sh -e
 
 . ci/travis/lib.sh
 . ci/travis/before_install_lib.sh

ci/travis/lib.sh

@@ -13,16 +13,22 @@ command_exists() {
 ensure_command_exists() {
 	local cmd="$1"
 	local package="$2"
+	local yes_confirm
 	[ -n "$cmd" ] || return 1
 	[ -n "$package" ] || package="$cmd"
 	! command_exists "$cmd" || return 0
 	# go through known package managers
 	for pacman in apt-get brew yum ; do
 		command_exists $pacman || continue
-		$pacman install -y $package || {
+		if [ "$pacman" = "brew" ] ; then
+			yes_confirm=
+		else
+			yes_confirm="-y"
+		fi
+		"$pacman" install $yes_confirm "$package" || {
 			# Try an update if install doesn't work the first time
-			$pacman -y update && \
-				$pacman install -y $package
+			"$pacman" $yes_confirm update && \
+				"$pacman" install $yes_confirm "$package"
 		}
 		return $?
 	done

python/iio/attr_updater.py

@@ -71,7 +71,7 @@ def sender(self):
             try:
                 self.message_port_pub(self.port, msg_dic)
             except:
-                print "Error: Failed to publish message"
+                print("Error: Failed to publish message")
                 return
 
             sleep(self.interval/1000)