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# Display current PATH
echo $PATH
# /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

# Find where a command lives
which python3
# /usr/bin/python3

which -a python3        # Show all matches in PATH
type python3            # Also shows aliases, builtins
command -v git          # Portable way to check if command exists

# Add a directory to PATH (current session only)
export PATH="$PATH:/opt/myapp/bin"

# Prepend (higher priority)
export PATH="/opt/myapp/bin:$PATH"

# Add to PATH permanently (append to ~/.bashrc)
echo 'export PATH="$HOME/.local/bin:$PATH"' >> ~/.bashrc

# Reload ~/.bashrc in current session
source ~/.bashrc
# Equivalent shorthand
. ~/.bashrc

# Create a local bin directory and add to PATH
mkdir -p ~/.local/bin
export PATH="$HOME/.local/bin:$PATH"

# Install a script to local bin
cp myscript.sh ~/.local/bin/myscript
chmod +x ~/.bashrc/myscript

# Source a .env file
# cat .env:
# export DB_HOST=localhost
# export DB_PASS=secret

source .env
echo $DB_HOST      # localhost

# Inspect all shell startup file locations
# /etc/profile          login, all users
# /etc/bash.bashrc      interactive, all users
# ~/.bash_profile       login, current user
# ~/.bashrc             interactive, current user
# ~/.bash_logout        on logout