MultiEnv: A small bash tool to handle multiple (possibly) clashing bash environments, e.g., different ROS workspaces

multienv_setup.sh

#!/bin/bash
#  ___  ___   _   _   _     _____   _   ____   __    _  __      __
# |   \/   | | | | | | |   |_   _| | | |  __| |  \  | | \ \    / /
# | |\  /| | | |_| | | |__   | |   | | | |__  |   \ | |  \ \  / / 
# |_| \/ |_| |_____| |____|  |_|   |_| |  __| | |\ \| |   \ \/ /  
#                                      | |__  | | \   |    \  /   
# v1.0 by Stefan Fabian                |____| |_|  \__|     \/    
#
# This script installs multienv, a small bash tool that allows you to easily switch between environments.
# For available commands run 'multienv help' after installation.
# Tab-completion is also supported!
#
# For example, let's say you have an environment using a catkin workspace overlaying the
# ROS (Robot Operation System) software stack.
# You would create an env named my_workspace:
#   multienv create my_workspace
#
# This would open up an editor with a shebang line already filled in, you would modify it to contain:
#   #!/bin/bash
#   source /home/user/workspace_path/devel/setup.bash
#
# Save the file and exit. Now, you've created an environment.
# To switch to it, run:
#   multienv switch my_workspace
#
# This will start a new shell session and source the script you created above.
# You do some work in that environment and after you're done, you want to switch the environment off again.
# For that, there's the special 'none' environment.
#   multienv switch none
#
# This will start a new shell session and not source anything.
# Alternatively, you could also switch to a different environment (after you created more than one).
# A new terminal will always start with the session that was last switched to.
# To switch only your currently active terminal use the --this option.
#
#  =========
#  CHANGELOG
#  =========
#  v1.0:
#     - Added reload command
#     - Fixed env switch changing directory to the user's home directory
#
MULTIENV_INSTALL_DIR=~/.multienv

NC='\033[0m'
RED='\033[0;31m'
GREEN='\033[0;32m'
BROWN='\033[0;33m'
BLUE='\033[0;34m'

function info() {
    echo -e "${BLUE}${1}${NC}"
}

function warn() {
    echo -e "${BROWN}${1}${NC}"
}

function success() {
    echo -e "${GREEN}${1}${NC}"
}

function error() {
    echo -e "${RED}${1}${NC}"
}

if [[ -d $MULTIENV_INSTALL_DIR ]]; then
  echo "It looks like multienv is already installed!"
  read -p "Proceed anyway? (Y/n): " MULTIENV_INSTALL_PROCEED
  if [[ $MULTIENV_INSTALL_PROCEED != "Y" && $MULTIENV_INSTALL_PROCEED != "y" ]]; then
    exit 0
  fi
fi

echo -e "\e[31m ___  ___  \e[33m _   _  \e[32m _    \e[36m _____  \e[34m _  \e[0m ____   __    _  __      __"
echo -e "\e[31m|   \/   | \e[33m| | | | \e[32m| |   \e[36m|_   _| \e[34m| | \e[0m|  __| |  \  | | \ \    / /"
echo -e "\e[31m| |\  /| | \e[33m| |_| | \e[32m| |__ \e[36m  | |   \e[34m| | \e[0m| |__  |   \ | |  \ \  / / "                                   
echo -e "\e[31m|_| \/ |_| \e[33m|_____| \e[32m|____|\e[36m  |_|   \e[34m|_| \e[0m|  __| | |\ \| |   \ \/ /  "                                   
echo "                                     | |__  | | \   |    \  /   "                                       
echo "v1.0 by Stefan Fabian                |____| |_|  \__|     \/    "
echo

info "> Creating directory"
mkdir -p $MULTIENV_INSTALL_DIR/envs

info "> Configuration"
echo "Would you like to enable write protection?"
echo "Write protection requires sudo privileges to create, edit, delete environments as the relevant files will be write protected from normal users to prevent malicious modification."
read -p "Enable? (Y/n): " MULTIENV_INSTALL_WRITE_PROTECTION

if [[ $MULTIENV_INSTALL_WRITE_PROTECTION == "y" || $MULTIENV_INSTALL_WRITE_PROTECTION == "Y" ]]; then
  success "Write protection enabled!"
else
  echo -e "Write protection ${RED}not${NC} enabled."
fi

info "> Unzipping content"
if [ -f $MULTIENV_INSTALL_DIR/multienv.sh ] && [ ! -w $MULTIENV_INSTALL_DIR/multienv.sh ]; then
  warn "Looks like you're reinstalling and write protection is enabled."
  warn "Removing write protection (temporarily unless not enabled this time) for update."
  sudo chattr -i $MULTIENV_INSTALL_DIR/multienv.sh
fi
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KiqRrdps1XZ5dZ+wSezbLyhWbFRsopJFcPcELHE9/VL5G1dbmcIEIQAA" | base64 -d | gzip -d > $MULTIENV_INSTALL_DIR/multienv.sh
if [ $? -ne 0 ]; then
  error "An error occured while unzipping!"
  exit 1
else
  success "Unzipped $MULTIENV_INSTALL_DIR/multienv.sh"
fi

if [[ $MULTIENV_INSTALL_WRITE_PROTECTION == "y" || $MULTIENV_INSTALL_WRITE_PROTECTION == "Y" ]]; then
  sudo chattr +i $MULTIENV_INSTALL_DIR/multienv.sh
  sudo chmod 555 $MULTIENV_INSTALL_DIR/envs
fi

info "> Append to .bashrc"
MULTIENV_SOURCE_COMMAND="source $MULTIENV_INSTALL_DIR/multienv.sh"
if [ ! -w ~/.bashrc ]; then
  error "Your .bashrc seems to be write protected. Good for security!"
  echo "However, that means you will have to add the following yourself:"
  echo "source $MULTIENV_INSTALL_DIR/multienv.sh"
  exit 0
fi

# Remove old source if exists
sed -i -z "s/$(echo -ne $MULTIENV_SOURCE_COMMAND | sed 's,/,\\/,g' | tr '\n' '^' | sed 's/\^/\\n/g')//g" ~/.bashrc
echo $MULTIENV_SOURCE_COMMAND >> ~/.bashrc

success "All done."

MultiEnv is a small bash tool that enables the separation of different console environments with minimal footprint.
You can create environments that consist of a few lines of bash that are sourced whenever the environment is loaded.
Switching environments is persistent between terminal sessions which means if you switch the environment and open a new terminal, the new terminal will also use the environment you switched to.

Use cases for this tool include the separation of different ROS or ROS 1 and ROS 2 workspaces.
Switching the environment will produce a clean bash where the other environment was never sourced. Bash history is preserved.

Changelog v0.9:

Added --this option for multienv switch ENV_NAME to switch only active terminal.
Fixed some security flaws that would have allowed to inject code to be run when multienv is sourced.

Update v1.0

• Added reload command that will reload the active environment and reset the environment.
• Fixed environment switch or reload resulting in a change of the current working directory back to the users home directory