Working notes on Management: Disk, File, Firewall, Memory, Network, and Permissions, and related topics.
Topics
Disk
df and du for disk space, directory sizes, and finding deleted files that still hold space.
File
Check mode bits, take ownership, and set executable or read permissions.
Firewall
Block an IP by appending a DROP rule on INPUT with iptables.
Memory
Inspect memory with /proc/meminfo, free, top, vmstat, and dmidecode.
Network
Static IP in /etc/network/interfaces, DNS in resolv.conf, networking restart, and ifconfig.
Permissions
ls -l file types and the owner, group, and other permission bits including setuid, setgid, and sticky.
Date and time
View and set timezone, hardware clock, and restart cron after a timezone change.
Uninstall
Purge a package with apt-get, then autoremove and autoclean leftover files.
Users and groups
Add and delete users and groups, passwords, ACLs, and sudoers.d.
Version
Show OS and kernel version with release files, lsb_release, /proc/version, and uname.
