a2server-2-tools: Use Debian's unar if available

scripts/a2server-2-tools.txt

@@ -65,7 +65,7 @@ fi
 # download and install The Unarchiver, for expanding Apple disk images
 # http://wakaba.c3.cx/s/apps/unarchiver.html
 
-if [[ ! -f /usr/local/bin/unar ]]; then
+if ! command -v unar >/dev/null; then
 
     echo "A2SERVER: Installing The Unarchiver..."
 
@@ -75,6 +75,11 @@ if [[ ! -f /usr/local/bin/unar ]]; then
         touch /tmp/a2server-packageReposUpdated
     fi
 
+    if apt-cache show unar &>/dev/null; then
+        # Debian package exists >= jessie.
+        sudo apt-get -y install unar
+    else
+        # Legacy binary tarballs for wheezy.
         if [[ $isRpi || $isDebian ]]; then
             sudo apt-get -y install libgnustep-base1.22
             sudo apt-get clean
@@ -84,7 +89,9 @@ if [[ ! -f /usr/local/bin/unar ]]; then
                 wget -qO- "http://appleii.ivanx.com/a2server/files/unar-debian7_x86.tgz" | sudo tar Pzx
             fi
         fi
-    if [[ ! -f /usr/local/bin/unar ]]; then
+
+        # If all else fails, compile from source.
+        if ! command -v unar >/dev/null; then
             sudo apt-get -y install build-essential
             sudo apt-get -y install libgnustep-base-dev libz-dev libbz2-dev
             sudo apt-get -y install libssl-dev libicu-dev unzip
@@ -103,6 +110,7 @@ if [[ ! -f /usr/local/bin/unar ]]; then
             rm -rf /tmp/unar
         fi
         sudo mandb &> /dev/null
+    fi
 else
     echo "A2SERVER: The Unarchiver has already been installed."
 fi