Replace manual file parsing with ssh-keygen -R which properly handles
both hashed (|1|...) and unhashed entries. macOS and many Linux systems
use HashKnownHosts by default, making the previous implementation unable
to remove entries.
Changes:
- Use ssh-keygen -R for each hostname instead of parsing the file
- Detect successful removal via "updated" in stdout
- Backup files are now .old (ssh-keygen default) instead of .bak
- Bracketed entries ([host]:port) now require exact format
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Riccardo Schirone