https://linux-tips.com/t/disabling-ups-beep-under-linux/592

root@proxmox:~# cat /etc/nut/upsd.users
[upsduser]
     password = password
     upsmon primary
     actions = SET
     instcmds = ALL

root@proxmox:~# cat /etc/nut/upsmon.conf
RUN_AS_USER root
MONITOR nutdev1@localhost 1 upsduser password master

MINSUPPLIES 1
SHUTDOWNCMD "/sbin/shutdown -h"
NOTIFYCMD /usr/sbin/upssched
POLLFREQ 2
POLLFREQALERT 1
HOSTSYNC 15
DEADTIME 15
POWERDOWNFLAG /etc/killpower

BATTERYLEVEL low 30

NOTIFYMSG ONLINE    "UPS %s is back online"
NOTIFYMSG ONBATT    "UPS %s is in battery mode"
NOTIFYMSG LOWBATT   "UPS %s battery is low"
NOTIFYMSG FSD       "UPS %s: forced shutdown in progress"
NOTIFYMSG COMMOK    "Communication with UPS %s is restored"
NOTIFYMSG COMMBAD   "Communication with UPS %s interrupted"
NOTIFYMSG SHUTDOWN  "Auto logout and shutdown proceeding"
NOTIFYMSG REPLBATT  "UPS %s battery needs to be replaced"
NOTIFYMSG NOCOMM    "UPS %s is not reachable"
NOTIFYMSG NOPARENT  "upsmon parent process died - shutdown impossible"

NOTIFYFLAG ONLINE   SYSLOG+WALL+EXEC
NOTIFYFLAG ONBATT   SYSLOG+WALL+EXEC
NOTIFYFLAG LOWBATT  SYSLOG+WALL
NOTIFYFLAG FSD      SYSLOG+WALL+EXEC
NOTIFYFLAG COMMOK   SYSLOG+WALL+EXEC
NOTIFYFLAG COMMBAD  SYSLOG+WALL+EXEC
NOTIFYFLAG SHUTDOWN SYSLOG+WALL+EXEC
NOTIFYFLAG REPLBATT SYSLOG+WALL
NOTIFYFLAG NOCOMM   SYSLOG+WALL+EXEC
NOTIFYFLAG NOPARENT SYSLOG+WALL

root@proxmox:~# cat /etc/nut/ups.conf
[nutdev1]
        driver = "usbhid-ups"
        port = "auto"
        vendorid = "0463"
        productid = "FFFF"
        product = "5E"
        vendor = "EATON"
        bus = "001"

root@proxmox:/etc/nut# cat upssched-cmd
#!/bin/sh

 case $1 in
       onbatt)
          logger -t upssched-cmd "UPS in Battery Mode"
          /usr/sbin/upsmon -c fsd
          ;;
        commbad_message)
          echo "UPS is no longer connected" | mailx -s "Proxmox: UPS Warning messaage" e-mail address for warning
          ;;
        online)
          logger -t upssched-cmd "UPS back Online"
          ;;
        commok_message)
          echo "UPS is reconnected" | mailx -s "Proxmox: UPS Warning messaage" e-mail address for warning
          ;;
        nocomm_message)
          echo "UPS is no longer available" | mailx -s "Proxmox: UPS Warning messaage" e-mail address for warning
          ;;
        shutdowncritical)
          logger -t upssched-cmd "UPS on battery critical, forced shutdown"
          ;;
        upsgone)
          logger -t upssched-cmd "UPS has been gone too long, can't reach"
          ;;
        shutdown_message)
          echo "Proxmox is shutting down" | mailx -s "Promox: UPS Warning messaage" e-mail address for warning
          ;;
       *)
          logger -t upssched-cmd "Unrecognized command: $1"
          ;;
 esac

systemctl restart nut-server

systemctl restart nut-monitor

root@proxmox:/etc/nut# upsc nutdev1
Init SSL without certificate database
battery.charge: 91
battery.runtime: 2459
battery.type: PbAc
device.mfr: EATON
device.model: 5E 2000i
device.type: ups
driver.name: usbhid-ups
driver.parameter.bus: 001
driver.parameter.pollfreq: 30
driver.parameter.pollinterval: 2
driver.parameter.port: auto
driver.parameter.product: 5E
driver.parameter.productid: FFFF
driver.parameter.synchronous: auto
driver.parameter.vendor: EATON
driver.parameter.vendorid: 0463
driver.version: 2.8.0
driver.version.data: MGE HID 1.46
driver.version.internal: 0.47
driver.version.usb: libusb-1.0.26 (API: 0x1000109)
input.voltage: 235.0
outlet.1.status: on
outlet.desc: Main Outlet
outlet.id: 1
outlet.switchable: no
output.frequency: 50.0
output.frequency.nominal: 50
output.voltage: 237.0
output.voltage.nominal: 230
ups.beeper.status: muted
ups.delay.shutdown: 20
ups.firmware: 02.06.0019
ups.load: 5
ups.mfr: EATON
ups.model: 5E 2000i
ups.power.nominal: 2000
ups.productid: ffff
ups.realpower: 80
ups.start.battery: yes
ups.status: OL
ups.timer.shutdown: -1
ups.vendorid: 0463