Having this issue on Linux machine trying to run command as a user who require /proc filesystem (such as top or htop) ?
[user@server ~]$ top top: /proc is not mounted, required for output data [user@server ~]$ htop Error: could not read procfs (compiled to look in /proc).
This usually happen because /proc lose his permission. Make sure it’s owned by root and group root and permissions set to read-execute for owner, group and everyone (r-xr-xr-x) or 555.
chown root:root /proc chmod 555 /proc