Install zsh on a machine, without sudo

install_zsh.sh

#!/bin/bash
set -euo pipefail
set -x

: "${TARGET:?usage: "TARGET=<HOME>" $0}"

NCURSES_VERSION=6.4
NCURSES_SOURCE="ncurses-$NCURSES_VERSION"
ZSH_VERSION=5.9
ZSH_SOURCE=zsh_source
ZSH_INST=$TARGET/zsh_inst

cd ~

# Download zsh
wget -O zsh.tar.xz https://sourceforge.net/projects/zsh/files/zsh/$ZSH_VERSION/zsh-$ZSH_VERSION.tar.xz/download
mkdir $ZSH_SOURCE
unxz zsh.tar.xz
tar -xvf zsh.tar -C $ZSH_SOURCE --strip-components 1

cd $ZSH_SOURCE

# Install ncurses - a dependency of zsh that may not be present on the machine
curl -LO https://mirrors.kernel.org/gnu/ncurses/$NCURSES_SOURCE.tar.gz
tar xf $NCURSES_SOURCE.tar.gz
cd $NCURSES_SOURCE
./configure --prefix="$TARGET/.local" --with-shared --without-debug --enable-widec
make -j"$(nproc)"
make install

cd ..

# Install zsh
CPPFLAGS="-I$TARGET/.local/include" LDFLAGS="-L$TARGET/.local/lib" ./configure --prefix="$ZSH_INST"
make -j"$(nproc)"
make install

# Test zsh
"$ZSH_INST/bin/zsh" --version