Set a Default Model with the ANTHROPIC_MODEL Env Var

If you always reach for the same model, stop passing --model on every command. The ANTHROPIC_MODEL environment variable sets your default so you never have to think about it.

# Add to your .zshrc or .bashrc
export ANTHROPIC_MODEL="claude-opus-4-6"

Now every Claude Code session uses that model automatically:

# No --model flag needed
claude "Refactor the payment service"
claude -p "Write a changelog entry for this diff"

You can still override it for individual commands — the flag always takes precedence over the environment variable:

# Override for a quick, cheap task
claude --model claude-haiku-4-5-20251001 "Rename this variable across the codebase"

# Override for something that needs maximum power
claude --model claude-opus-4-6 "Design the architecture for this new feature"

This is particularly useful if you're testing a newly released model across your daily workflow — update the env var once and every session picks it up automatically. When you're done evaluating, change it back in one place.

# Confirm which model is active
echo $ANTHROPIC_MODEL

Set it in your shell profile once, and never think about it again.