He draws a line in the sand.

I prefer using a command-line interface for programming.

Command-line interfaces are widely used in software development.

The passenger dedicated line is a convenient way to travel.

The passenger dedicated lines are always crowded during rush hour.

The horse was diagnosed with white line disease.

The scatter plot shows multiple lines of best fit.

Bright-line rules provide clear guidelines for decision-making.

The capital market lines provide a visual representation of the risk and return trade-off for different portfolios.

I heard some hilarious chat-up lines at the party last night.