The request system configuration rescue save command in Junos OS saves the most recently committed configuration as the rescue configuration. This rescue configuration can be used to recover the device if future configurations cause issues. It ensures there is a stable, known-good configuration to fall back on, which is crucial in network management and troubleshooting.
Reference:
"rescue : save configurations as the rescue: request system configuration save .................( saves the current configs as a rescue configs )" from Useful Juniper Commands.txt.
Juniper official documentation: Configuring and Activating a Rescue Configuration.