Red Hat System Administration I

[student@workstation ~]$ ssh student@serverb
...output omitted...
[student@serverb ~]$ su -
Password: redhat
[root@serverb ~]# 

1. Use the mkdir command to create a directory called /home/techdocs.

   [root@serverb ~]# mkdir /home/techdocs

1. Use the chown command to change the group ownership for the /home/techdocs directory to the techdocs group.

   [root@serverb ~]# chown :techdocs /home/techdocs

1. Use the su command to switch to the tech1 user.

   [root@serverb ~]# su - tech1
   [tech1@serverb ~]$ 

2. Use touch to create a file named techdoc1.txt in the /home/techdocs directory.

   [tech1@serverb ~]$ touch /home/techdocs/techdoc1.txt
   touch: cannot touch '/home/techdocs/techdoc1.txt': Permission denied

   Note

   Note that even though the /home/techdocs directory is owned by techdocs and tech1 is part of the techdocs group, it is not possible to create a new file in that directory. This is because the techdocs group does not have write permission. Use the ls -ld command to show the permissions.

   [tech1@serverb ~]$ ls -ld /home/techdocs/
     drwxr-xr-x. 2 root techdocs 6 Feb  5 16:05 /home/techdocs/

1. Exit from the tech1 user shell.

   [tech1@serverb ~]$ exit
   logout
   [root@serverb ~]# 

2. Use the chmod command to set the group permission for the /home/techdocs directory. On the /home/techdocs directory, configure setgid (2), read/write/execute permissions (7) for the owner/user and group, and no permissions (0) for other users.

   [root@serverb ~]# chmod 2770 /home/techdocs

[root@serverb ~]# ls -ld /home/techdocs
drwxrws---. 2 root techdocs 6 Feb 4 18:12 /home/techdocs/ 

Note that the techdocs group now has write permission.

1. Switch to the tech1 user. Use touch to create a file called techdoc1.txt in the /home/techdocs directory. Exit from the tech1 user shell.

   [root@serverb ~]# su - tech1
   [tech1@serverb ~]$ touch /home/techdocs/techdoc1.txt
   [tech1@serverb ~]$ ls -l /home/techdocs/techdoc1.txt
   -rw-rw-r--. 1 tech1 techdocs 0 Feb  5 16:42 /home/techdocs/techdoc1.txt
   [tech1@serverb ~]$ exit
   logout
   [root@serverb ~]# 

2. Switch to the tech2 user. Use the echo command to add some content to the /home/techdocs/techdoc1.txt file. Exit from the tech2 user shell.

   [root@serverb ~]# su - tech2
   [tech2@serverb ~]$ cd /home/techdocs
   [tech2@serverb techdocs]$ echo "This is the first tech doc." > techdoc1.txt
   [tech2@serverb techdocs]$ exit
   logout
   [root@serverb ~]# 

3. Switch to the database1 user. Use the echo command to append some content to the /home/techdocs/techdoc1.txt file. Notice that you will get a Permission Denied message. Use the ls -l command to confirm that database1 does not have access to the file. Exit from the database1 user shell.

   The following echo command is very long and should be entered on a single line.

   [root@serverb ~]# su - database1
   [database1@serverb ~]$ echo "This is the first tech doc." >> /home/techdocs/techdoc1.txt
   -bash: /home/techdocs/techdoc1.txt: Permission denied
   [database1@serverb ~]$ ls -l /home/techdocs/techdoc1.txt
   ls: cannot access '/home/techdocs/techdoc1.txt': Permission denied
   [database1@serverb ~]$ exit
   logout
   [root@serverb ~]# 

1. Determine the umask of the student user. Use the su - student command to switch to student login shell. When done exit from the shell.

   [root@serverb ~]# su - student
   [student@serverb ~]$ umask
   0002
   [student@serverb ~]$ exit
   logout
   [root@serverb ~]# 

2. Create the /etc/profile.d/local-umask.sh file with the following content to set the umask to 007 for users with a UID greater than 199 and with a username and primary group name that match, and to 022 for everyone else:

   # Overrides default umask configuration
   if [ $UID -gt 199 ] && [ "`id -gn`" = "`id -un`" ]; then
       umask 007
   else
       umask 022
   fi

3. Log out of the shell and log back in as student to verify that global umask changes to 007.

   [root@serverb ~]# exit
   logout
   [student@serverb ~]$ exit
   logout
   Connection to serverb closed.
   [student@workstation ~]$ ssh student@serverb
   ...output omitted...
   [student@serverb ~]$ umask
   0007