Installs rustup as a system-wide toolchain manager

install_rustup.sh

#!/bin/zsh

# Rustup doesn't have an easy "system-wide" approach to installation since it
# requires $CARGO_HOME for locating the binary folder. Here, we define
# `system-wide` as requiring `sudo-only` permission, i.e. `rustup install
# toolchain ...` breaks without `sudo`.
#
# The trick is thus to somehow "envelope" Rustup in another script so that it
# uses a "system-wide" cargo home instead of the default one whenever it's
# called.
#
# This script also does some other convenient tasks such as adding the real
# Cargo home to profiles.
#
# This script is configurable:
#
#  - Set `RUST_HOME` to the directory you want rustup to install toolchains and binaries to. [default=/usr/local/rust]
#  - Set `CARGO_HOME` to the home directory you want Cargo to use. [default=Cargo's default]
#  - Set `NO_PATH` to disable adding the Cargo home to the path. Only bash and zsh are supported. [default=false]
#
# This script must be run in sudo mode.
#

set -e

########################
# System installations #
########################

if [ -z ${RUST_HOME+x} ]; then
	rust_home=/usr/local/rust
else
	rust_home=$RUST_HOME
fi

# Add system-wide rust home to profile.
for profile in /etc/zshrc /etc/bashrc /etc/profile; do
	if ! grep -q "RUSTUP_HOME" $profile; then
		cat <<EOF >>$profile

# Set system-wide rust home
RUSTUP_HOME=$rust_home; export RUSTUP_HOME
EOF
	fi
done

# Source the profile.
source /etc/zshrc

# Add system-wide rust home to sudo.
cat <<EOF >/etc/sudoers.d/cargo
Defaults        env_keep += "RUSTUP_HOME"
EOF

# Add system-wide rust home to paths.
cat <<EOF >/etc/paths.d/cargo
$rust_home/bin
EOF

# Install rustup.
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | env CARGO_HOME=$rust_home sh -s -- -y --no-modify-path --profile minimal

# Envelope rustup.
cat <<EOF >/usr/local/bin/rustup
#!/bin/sh
CARGO_HOME=$rust_home exec $rust_home/bin/rustup "\$@"
EOF
chmod +x /usr/local/bin/rustup

######################
# User installations #
######################

# Set up user Cargo home.
if [ -z ${CARGO_HOME+x} ]; then
	user_cargo_home="\$HOME/.cargo" # This is the default Cargo home used by Cargo.
else
	user_cargo_home=$CARGO_HOME
fi

# Either we are using zsh or bash
if [ -z ${BASH+x} ]; then
	user_profile=$HOME/.zshrc
else
	user_profile=$HOME/.bashrc
fi

# Add user Cargo home to profile.
if [ -z ${NO_PATH+x} ]; then

	# Set up user bin directory.
	cat <<EOF >>$user_profile

export PATH=$user_cargo_home/bin:\$PATH
EOF

fi