1. The suspend command: shell build-in function to halt the current shell.

2. To terminate the process number 598, you can run the below command:

    A. kill 598         B. kill -TERM 598        C.    Kill -SIGTERM 598

3. The rusers command: who is logged in on remote machines.

4. Kernel is for device management.

5. The reboot command: restart the operating system. the synopsis as below:

    /usr/sbin/reboot  [-d l p q]  [boot arguments]

Remark: the delimiter `--` (two hyphens) must be used to separate the options of reboot from the arguments of boot.

For example:     # reboot -- -rv

                        # reboot -dl -- -i

6. Find a file whose size is larger than 1 kilobytes:

# find /export/home -size +2 -print

Remark: 默认情况下，是以block 为单位，每个block是512 bytes, 因此上例中带的是 +2.

7.  ls -F  marks directories with a trailing slash (/), doors with a trailing greater-than sign (>), executable files with a trailing asterisk (*), FIFOs with a trailing vertical bar (|), symbolic links with a trailing at-sign (@), and AF_UNIX address family sockets with a trailing equals sign (=).

8. uuencode, uudecode -- encode a binary file, or decode its encoded representation.

9. The /usr/share/lib/terminfo directory is a database that describes the capabilities of devices such as terminals and printers.

10. The dd and ufsdump commands can integrate an incremental backup feature, and cpio and tar don't .

11. The ps command:

      -a   Lists information about all processes most frequently requested: all those except process group leaders and processes not associated with a terminal

      -A   Lists information for all processes.  Same as the "-e"

      -e   Lists information about every process now runing.

      -f    Generates a full listing.

      -l    Generates a long listing.

     -t  term     Lists only process data associated with the term.

     -u  uidlist    Lists only process data whose effective user ID number or login name is given in uidlist.

     -U uidlist     Lists only information for processes whose real user ID numbers or login names are given in uidlist. 

12.  To raise the priority of a user process, you can use  "nice" and "priocntl" command.

13.  Sticky Bit has no affect to the file owner, the owner of the directory and root.

14.  The NIS+ default security level is 2.

15.  The superblock contains  most of the information about a file system.