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Answers to Even-numbered Exercises
2. How would you communicate each of the following messages?
1.

Ho r mode?

a. The system is coming down tomorrow at 6:00 in the evening for periodic maintenance.
Use the /etc/motd file and/or email. Alternatively, you can include the message in a shutdown command.
b. The system is coming down in five minutes.
Use wall or include the message in a shutdown command.
c. Zach’s jobs are slowing the system down drastically, and he should postpone them.
Use write or talk.
d. Zach’s wife just had a baby girl.
Use the motd file and/or email.
4. How would you allow a user to execute a specific, privileged command without giving the user the root password?
3.

Whgs in?

You can create a setuid program that belongs to a group that only the user who is to execute it belongs to and that has no permissions for other users.
6. How can you disable SELinux?
5.

How dileges?

Either use the SELinux tab of the Security Level Configuration window displayed by system-config-securitylevel to change the SELinux setting to
Disabled or put the following line in /etc/sysconfig/selinux:
SELINUX=disabled

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Then reboot the system.
8. Give the command
7.

to remember.

$ /bin/fuser -uv /

What does the output list? Why is it so long? Give the same command while working with root privileges (or ask the system administrator to do so and email you the results). How does this list differ from the first? Why is it different?
This command displays a list of processes using the root filesystem. The list is long because all files on the system are children of root; therefore this command lists all processes using any file or filesystem.
The first list shows only processes owned by the user who gives the command. When the command is run by a user working with root privileges, the output shows all