ACIT 2421 - FINAL

Which command sets "other" permissions to r-x?

chmod o=rx file

Which command sets "other" permissions to r-x?

chmod o=rx file

Which command sets "other" permissions to r-x?

chmod o-r-w file

Which command sets "other" permissions to r-x?

chmod o=r+x file

Which numeric chmod sets "other" to r-x?

chmod 775 file

Only one set (user, group, other) can be changed at once using symbolic method.

False

Which methods can chmod use? (2)

octal; symbolic

The chown command can change both owner and group.

True

The user sysadmin can read a file because they own it.

True

The user sysadmin can change permissions because they own it.

True

Octal values for permissions

r=4, w=2, x=1

Which permissions allow all users to add, view, delete in a directory?

777

A user cannot delete a file if they do not own it.

False

Execute permission on a directory allows (3)

cd into directory; use in path; create files with write

Execute permission on a file allows you to

run the file as a script

Who can use chgrp on a file?

file owner and root

Who can change user ownership with chown?

only root

Who can use chmod on a file?

file owner and root

Execute permission is never set by default on files.

True

Which commands set owner to sam and group to administrators?

chown sam.administrators myFile; chown sam:administrators myFile

Changing group ownership with chown is root only.

False

File owner always has same or higher permissions than others.

False

Which command lists hidden files with ownership?

ls -la

The /tmp directory allows any user to create temporary files.

True

Sticky bit purpose

prevents deleting files you don’t own in shared directories

Set sticky bit on /shared

chmod 1777 /shared

Setuid allows

run command as file owner

Set setuid on /usr/bin/program

chmod 4755 /usr/bin/program

Setgid allows (2)

run as group owner; new files inherit directory group

Set setgid on /shared

chmod 2777 /shared

Which listing shows setgid on directory?

drwxrwsrwx

Effect of setgid on directory

new files inherit directory group

Deleting source breaks hard link.

False

Hard link must be on same filesystem.

True

Deleting source breaks symbolic link.

True

Symbolic link must be on same filesystem.

False

Create a hard link

ln file link

Create a symbolic link

ln -s file link

Which ls commands show directory itself only? (2)

ls -ld; ls -d

Which directories allow any user temp files? (2)

/tmp; /var/tmp

Which files contain user account information? (choose two)

/etc/passwd /etc/shadow

Which user can view the /etc/shadow file?

The root user

Which command will display the UID, GID and groups your current user belongs to?

id

Each user belongs to at least one group.​ True or False?

True

Which command will display the users that are currently logged in to the system?

who

The sudo command allows regular users to…

…execute commands as another user.

Which of the following commands will display the group(s) a user belongs to?

id

Which of the following commands will display the groups that the user bob belongs to?

id bob

The /etc/group file follows what structure?

group_name:password_placeholder:GID:user_list

A GID is associated with a group name. True or False?

True

A user can belong to…

At least 16 groups

Sudo privileges can be used to specify which user can use the sudo command to execute commands as other users. True or False?

True

In distributions that do not allow the root user to login directly or via the su command… True or False?

True

Which of the following commands will display how long the system has been running since the last boot? (choose two)

uptime w

The /etc/shadow file contains plain-text passwords. True or False?

False

Which command can be used to view the /etc/passwd file entries?

getent

All Linux systems allow administrators to log in as root. True or False?

False

What is the default user for the su command?

The root user

Which command would allow a user to execute commands as root?

sudo

File permissions cannot be edited by the root user. True or False?

False

Which command is used to display only the user’s primary group?

id -g

Traditional UNIX systems allowed users to belong to how many groups?

16

What would an account with the UID 376 typically be used for?

System service access.

Usernames cannot be the same as group names. True or False?

False

To display the group(s) a user belongs to, use this command:

id

Which command will display the groups that the root user belongs to?

id root

Value of 0 in the “minimum” password aging field means the user cannot change their password. True or False?

False

The “Epoch” began on January 1, 1970. True or False?

True

The last command displays reboot records…

By default

Sudo privileges allow users to execute commands as another user. True or False?

True

When using sudo, the command prompts for the user’s own password. True or False?

True

The first line of this command displays uptime since reboot.

w

The /etc/shadow file contains encrypted passwords. True or False?

True

Which command can be used to view the /var/log/wtmp file entries?

last

UIDs 1-499 are usually reserved for what kind of users?

System accounts, such as server processes

If a user is deleted, the files and directories that the user owned…

…will show a UID as the owner, but not user name.

Which option for useradd specifies UID?

-u

Which option for useradd specifies supplementary groups?

-G

On a system that does not use UPG… True or False?

True

Which command adds group extra to bob’s secondary groups (without removing others)?

usermod -aG extra bob

Which options for usermod specify group IDs? (choose two)

-G -g

For non-root users, passwd can only change their own password. True or False?

True

groupmod can change a group name. True or False?

True

groupmod can change a group GID. True or False?

True

groupmod can add users to a group. True or False?

False

Which command modifies a group?

groupmod

Which command shows most recent logins?

last

Which file contains encrypted user password info?

/etc/shadow

Which file contains user IDs?

/etc/passwd

Which file does groupadd use to determine new GID?

/etc/group

Which command prevents bob from logging in?

usermod -L bob

What directory contains user home directories?

/home

GIDs under 500 (or 1000) are reserved for what?

System use

If a user is deleted, files they owned…

…may be important for others in the organization

Which option sets a different primary group in useradd?

-g

On a system using UPG, UID must not equal GID. True or False?

False

Which option unlocks a user account?

-U

Which option sets login shell in useradd?

-s

Which command adds extra group to jane (keeping others)?

usermod -aG extra jane

Which option sets primary group ID in usermod?

-g