a. Basic commands i. File or file content related commands 1. wc 2. md5sum 3. sha1sum 4. dd 5. file ii. Search type commands 1. locate 2. find 3. grep 4. which 5. whereis iii. Process control related commands 1. bg 2. fg 3. jobs 4. ps 5. kill 6. killall iv. Environment variables related commands 1. set 2. export 3. echo v. Miscellaneous commands 1. alias 2. unalis 3. strace 4. ldd 5. script 6. xargs 7. history b. Superuser commands i. System status commands 1. updatedb ii. Network related commands 1. nc 2. scp 3. ssh iii. Administration commands 1. sync 2. mount 3. umount 4. chmod 5. chown