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Handle SIGINT Cleanup in a CLI

Trap interrupt signals to remove temporary files and flush progress so Ctrl-C does not leave a broken state.

const tmp = makeTempDir();
let done = false;
function cleanup() {
  if (done) return; done = true;
  rmSync(tmp, { recursive: true, force: true });
  process.exit(130);
}
process.on('SIGINT', cleanup);
process.on('SIGTERM', cleanup);

tool long-job &
sleep 1 && kill -INT %1
ls /tmp | grep tool-tmp || echo 'no leftovers'

What this recipe does

Install signal handlers that clean up temporary resources before exiting.

Interrupting a long CLI run leaves partial temp files and a half-written output that confuses the next run.

Prerequisites

• A CLI that writes temporary files
• A way to register signal handlers
• A cleanup routine

Procedure

1. Register handlers that clean up then exit.

const tmp = makeTempDir();
let done = false;
function cleanup() {
  if (done) return; done = true;
  rmSync(tmp, { recursive: true, force: true });
  process.exit(130);
}
process.on('SIGINT', cleanup);
process.on('SIGTERM', cleanup);

Expected result: Ctrl-C removes temporary resources and exits with the conventional code.

2. Verify no leftovers remain after an interrupt.

tool long-job &
sleep 1 && kill -INT %1
ls /tmp | grep tool-tmp || echo 'no leftovers'

Expected result: The temp directory is gone, proving cleanup ran on interrupt.

How to confirm it worked

Run the commands above and confirm every expected result in order. If a step does not produce the stated output, use the troubleshooting notes before continuing. A passing run shows interrupting the CLI leaves no temporary files and returns the conventional exit code.

Troubleshooting

Cleanup runs twice — Guard cleanup with an idempotency flag so both SIGINT and SIGTERM are safe.

Exit code wrong — Exit with 130 for SIGINT so scripts can distinguish interruption.

Limitations

• SIGKILL cannot be trapped.
• Async cleanup in handlers is limited.
• Requires careful exit code semantics.