Tools: Give a better chance on default install to get the right package version

Tools/environment_install/install-prereqs-ubuntu.sh

@@ -85,15 +85,26 @@ elif [ ${RELEASE_CODENAME} == 'trusty' ]; then
     SITLFML_VERSION="2"
     SITLCFML_VERSION="2"
 else
-    # Extract the floating point number that is the version of the libcsfml package.
-    SITLCFML_VERSION=`dpkg-query --search libcsfml-audio | cut -d":" -f1 | grep libcsfml-audio | head -1 | grep -Eo '[+-]?[0-9]+([.][0-9]+)?'`
-    # And same for libsfml-audio.
-    SITLFML_VERSION=`dpkg-query --search libsfml-audio | cut -d":" -f1 | grep libsfml-audio | head -1 | grep -Eo '[+-]?[0-9]+([.][0-9]+)?'`
+    # We assume APT based system, so let's try with apt-cache first.
+    SITLCFML_VERSION=$(apt-cache search -n '^libcsfml-audio' | cut -d" " -f1 | head -1 | grep -Eo '[+-]?[0-9]+([.][0-9]+)?')
+    SITLFML_VERSION=$(apt-cache search -n '^libsfml-audio' | cut -d" " -f1 | head -1 | grep -Eo '[+-]?[0-9]+([.][0-9]+)?')
+    # If we cannot retrieve the number with apt-cache, try a last time with dpkg-query
+    re='^[+-]?[0-9]+([.][0-9]+)?$'
+    if ! [[ $SITLCFML_VERSION =~ $re ]] || ! [[ $SITLFML_VERSION =~ $re ]] ; then
+        # Extract the floating point number that is the version of the libcsfml package.
+        SITLCFML_VERSION=$(dpkg-query --search libcsfml-audio | cut -d":" -f1 | grep libcsfml-audio | head -1 | grep -Eo '[+-]?[0-9]+([.][0-9]+)?')
+        # And same for libsfml-audio.
+        SITLFML_VERSION=$(dpkg-query --search libsfml-audio | cut -d":" -f1 | grep libsfml-audio | head -1 | grep -Eo '[+-]?[0-9]+([.][0-9]+)?')
+    fi
 fi
 
 # Check whether the specific ARM pkg-config package is available or whether we should emulate the effect of installing it.
-ARM_PKG_CONFIG_NOT_PRESENT=`dpkg-query --search pkg-config-arm-linux-gnueabihf |& grep -c "no path found matching pattern"`
-if [ $ARM_PKG_CONFIG_NOT_PRESENT -eq 1 ]; then
+# Check if we need to manually install libtool-bin
+ARM_PKG_CONFIG_NOT_PRESENT=0
+if [ -z "$(apt-cache search -n '^pkg-config-arm-linux-gnueabihf')" ]; then
+    ARM_PKG_CONFIG_NOT_PRESENT=$(dpkg-query --search pkg-config-arm-linux-gnueabihf |& grep -c "dpkg-query:")
+fi
+if [ "$ARM_PKG_CONFIG_NOT_PRESENT" -eq 1 ]; then
     INSTALL_PKG_CONFIG=""
     # No need to install Ubuntu's pkg-config-arm-linux-gnueabihf, instead install the base pkg-config.
     sudo apt-get install pkg-config
@@ -115,7 +126,6 @@ PYTHON_PKGS="future lxml pymavlink MAVProxy pexpect flake8"
 if [[ $SKIP_AP_EXT_ENV -ne 1 ]]; then
   PYTHON_PKGS="$PYTHON_PKGS pygame intelhex"
 fi
-# Check for
 ARM_LINUX_PKGS="g++-arm-linux-gnueabihf $INSTALL_PKG_CONFIG"
 # python-wxgtk packages are added to SITL_PKGS below
 SITL_PKGS="libtool libxml2-dev libxslt1-dev ${PYTHON_V}-dev ${PYTHON_V}-pip ${PYTHON_V}-setuptools ${PYTHON_V}-numpy ${PYTHON_V}-pyparsing ${PYTHON_V}-psutil"