Ubuntu Swift-2.2 installer

install_swift-2.2.sh

#!/bin/bash

TARBALL="swift-2.2.tar.gz"
TARBALL_SIG="swift-2.2.tar.gz.sig"
SWIFT_TARBALL_URL="https://swift.org/builds/ubuntu1404/swift-2.2-SNAPSHOT-2015-12-01-b/swift-2.2-SNAPSHOT-2015-12-01-b-ubuntu14.04.tar.gz"
SWIFT_TARBALL_SIG_URL="https://swift.org/builds/ubuntu1404/swift-2.2-SNAPSHOT-2015-12-01-b/swift-2.2-SNAPSHOT-2015-12-01-b-ubuntu14.04.tar.gz.sig"
DESTDIR="/opt/swift-2.2"

if [ ! -e "$TARBALL" ]; then
    wget "$SWIFT_TARBALL_URL" -O "$TARBALL"
fi

if [ ! -e "$TARBALL_SIG" ]; then
    wget "$SWIFT_TARBALL_SIG_URL" -O "$TARBALL_SIG"
fi

gpg --keyserver hkp://pool.sks-keyservers.net \
      --recv-keys \
      '7463 A81A 4B2E EA1B 551F  FBCF D441 C977 412B 37AD' \
      '1BE1 E29A 084C B305 F397  D62A 9F59 7F4D 21A5 6D5F'
gpg --keyserver hkp://pool.sks-keyservers.net --refresh-keys Swift

LANG=C gpg --verify swift-2.2.tar.gz.sig | grep "BAD signature"
if [ $? -eq 0 ]; then
    echo "Bad signature, stop to install."
    exit -1
fi

if [ ! -e "$DESTDIR" ]; then
    tar xf $TARBALL
    sudo mv swift-2.2-SNAPSHOT-2015-12-01-b-ubuntu14.04 "$DESTDIR"
fi
sudo apt-get install clang

echo
echo "If you are using bash, please add the following text in ~/.bashrc"
echo "If you are using zsh, the file is ~/.zshrc"
echo
echo "export PATH=$DESTDIR/usr/bin:\${PATH}"
echo

exit 0