Vim Backup Files vs Swap Files: Should Vim Auto‑Delete Backups After Recovery?

Answer the Question First

Should Vim automatically delete <file>~ after a successful recovery?

No. Vim keeps the backup file untouched after a crash recovery. The backup is only removed when a subsequent write operation overwrites it or when you explicitly delete it.

Why Vim Behaves This Way

• Backups provide a safety net for accidental data loss or unintended edits.
• The swap file (.swp) is the only file Vim removes automatically on a normal exit; it is left after a crash.
• Automatic deletion would erase the ability to recover a previous state if the user later changes their mind.

Confirmed Facts (from Vim help)

help backup
help backupcopy
help backupdir

• With set backup, Vim writes <file>~ before saving the new content.
• With set backupcopy=yes, the backup file is overwritten by the new content, effectively deleting the old backup.
• With set backupcopy=no (default), Vim renames the old file to <file>~ and creates a new backup on the next write.
• Swap files are removed automatically on normal Vim exit; they remain after a crash or forced kill.

How to Verify the Backup After Recovery

1. Start Vim with set backup enabled.
2. Open a file, make a change, and exit normally to create a backup.
3. Simulate a crash (e.g., kill -9 $$ from another terminal) while editing.
4. Re‑open the file in Vim; it will recover from the swap file.
5. Check the backup file:

   diff <file> <file>~
   # If diff shows differences, the backup still contains the pre‑edit state.
   

Optional Cleanup: Overwrite Backups Instead of Keeping Them

If you prefer Vim to keep only the most recent backup, add this to your vimrc:

set backup
set backupcopy=yes
set backupdir=$HOME/.vim/backup

• backupdir can point to a temporary or low‑space directory.
• With backupcopy=yes, the old backup is overwritten, so only one backup file exists per original file.
• Be careful: this removes the ability to retrieve older revisions.

When to Keep or Delete Backups Manually

• If you rely on backups for version history, keep them and delete manually when you no longer need them.
• For scripts that clean up old backups, use a cron job that deletes files older than a certain age, e.g.:

  find $HOME/.vim/backup -type f -mtime +30 -delete
  

Missing Diagnostic Detail

Do you want Vim to keep a history of backups (e.g., for audit or rollback purposes) or would you prefer it to overwrite them automatically? This choice determines whether backupcopy=yes is suitable for your workflow.