Quark Installer

#!/usr/bin/env sh
set -e

python_version="python2.7"

q3k_install_root="${HOME}/datawire"

is_python_installed () {
  amsg "  Checking if python is installed: "
  if command -v python > /dev/null 2>&1; then
    msgln "OK"
  else
    msgln "Not Installed. Please install python on your system."
    exit 1
  fi
}

is_pip_installed () {
  amsg "  Checking if pip is installed: "
  if command -v pip > /dev/null 2>&1; then
    msgln "OK"
  else
    msgln "Not Installed. Please install python pip on your system."
    exit 1
  fi
}

is_virtualenv_installed () {
  amsg "  Checking if virtualenv is installed: "
  if command -v virtualenv > /dev/null 2>&1; then
    msgln "OK"
  else
    msgln "Not Installed. Please install virtualenv on your system."
    exit 1
  fi
}

msgln () {
  printf "%s\n" "$1"
}

amsg () {
  printf "%s" "--> $1"
}

amsgln () {
  printf "%s\n" "--> $1"
}

amsgln "Performing installation environment sanity checks..."
is_python_installed 
is_pip_installed
is_virtualenv_installed

amsgln "Creating Datawire Quark installation directory..."
mkdir -p ${q3k_install_root}
virtualenv -q --python ${python_version} ${q3k_install_root}/quark/virtualenv

amsgln "Installing Datawire Quark..."
. ${q3k_install_root}/quark/virtualenv/bin/activate
pip --quiet install datawire-quark
deactivate 

cat <<- EOF > ./q3kc
	#!/usr/bin/env sh
	set -e

	. ${q3k_install_root}/quark/virtualenv/bin/activate
	quark \${@:1}
	deactivate
EOF

amsgln "Done!"

Looks great! Some suggestions are to write it so it works in sh not bash (for example on Ubuntu, bash is the default for terminal windows but not for shell scripts since /bin/sh is dash on Ubuntu). Take a look at what I wrote here https://github.com/datawire/datawire-connect/blob/installer/install.sh for an example.