Use of /etc/passwd-, /etc/shadow-, /etc/group- [closed]

These are backups of previous versions.

Manual pages show these files and states:

/etc/passwd-

Backup file for /etc/passwd.

/etc/shadow-

Backup file for /etc/shadow.

Note that this file is used by the tools of the shadow toolsuite, but not by all user and password management tools.

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