How can I get accurate information about disk space used/available in Big Sur via the command line?
diskutil info /dev/disk3s1s1 seems to do the trick for me:
Container Total Space: 994.7 GB (994662584320 Bytes) (exactly 1942700360 512-Byte-Units)
Container Free Space: 635.1 GB (635058384896 Bytes) (exactly 1240348408 512-Byte-Units)
(other output snipped)
My output from df -H:
/dev/disk3s1s1 995G 15G 634G 3% 568975 9712932825 0% /
/dev/disk3s5 995G 335G 634G 35% 1363090 9712138710 0% /System/Volumes/Data