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# List all environment variables env printenv # Print a specific variable printenv HOME echo $HOME echo $USER echo $SHELL # Assign a shell-local variable (NOT exported) MY_VAR="hello" bash -c 'echo $MY_VAR' # Empty — not exported # Export a variable (available to child processes) export MY_VAR="hello" bash -c 'echo $MY_VAR' # Prints: hello # Export and assign in one step export API_URL="https://api.example.com" # Check if a variable is set if [[ -n "${MY_VAR:-}" ]]; then echo "MY_VAR is set to: $MY_VAR" fi # Temporarily override a variable for one command LANG=C ls --help # Show common important variables echo "Home: $HOME" echo "User: $USER" echo "Shell: $SHELL" echo "Editor: ${EDITOR:-not set}" echo "Term: $TERM" echo "Path: $PATH" # Unset a variable unset MY_VAR # Store variable in a script-friendly way using .env file # cat .env: # DB_HOST=localhost # DB_PORT=5432 # Source (load) the .env file into current shell # source .env OR . .env
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