RedHat EX200 問題集

質問 1：
Install dnf-automatic and enable automatic daily update checks.
正解：
See the solution below in Explanation.
Explanation:
Solution:
dnf install -y dnf-automatic
systemctl enable --now dnf-automatic.timer
systemctl list-timers --all | grep dnf
Detailed Explanation:
* dnf-automatic provides automated update checking and installation features.
* The timer unit schedules the checks.
* RHEL 10 DNF documentation specifically documents the dnf-automatic timer units. ( Red Hat Documentation )

質問 2：
Create a script to search for files
* Create a script named myresearch
* Place the script under /usr/local/bin
* The script is used to search for all files under /usr that are smaller than 10 MB and have group write permission, and place these files into /root/myfiles
正解：
Solution:
mkdir /root/myfiles
vim /usr/local/bin/myresearch
#!/bin/bash
find /usr -type f -and -size -10M -and -perm -2000 -exec cp -a {} /root/myfiles \;
:wq
chmod +x /usr/local/bin/myresearch
bash /usr/local/bin/myresearch
ll -h /root/myfiles
Script explanation:
(#!/bin/bash): #! is a conventional marker that tells the system which interpreter should be used to execute the script.
/bin/bash means the script is executed using the default Bash shell.
Here, a for loop is needed to iterate over the found GIDs (group IDs) for processing.
(awk -F':' '{print $3}' /etc/group):
awk is used to split and process text.
-F specifies the field separator.
":" indicates that the colon is used as the delimiter.
{print $3} prints the third field (the group ID).

質問 3：
System Optimization Configuration
Choose the recommended tuned configuration set for your system and set it as default.
正解：
Solution:
# Install and enable tuned
[root@node2 ~]# yum -y install tuned
[root@node2 ~]# systemctl enable tuned
[root@node2 ~]# systemctl restart tuned
# Check the recommended configuration scheme for the system
[root@node2 ~]# tuned-adm recommend
virtual-guest
# Switch to the specified configuration scheme
[root@node2 ~]# tuned-adm profile virtual-guest
# Check the current configuration scheme
[root@node2 ~]# tuned-adm active
Current active profile: virtual-guest

質問 4：
Configure AutoFS to automount two NFS shares under /automount.
正解：
See the solution below in Explanation.
Explanation:
Solution:
dnf install -y autofs
mkdir -p /automount
echo "/automount /etc/auto.automount --timeout=30" > > /etc/auto.master
echo "public -ro,sync nfs.lab.example.com:/public" > > /etc/auto.automount
echo "private -rw,sync nfs.lab.example.com:/private" > > /etc/auto.automount
systemctl enable --now autofs
Detailed Explanation:
* /etc/auto.master defines the main AutoFS map.
* /etc/auto.automount defines the indirect map entries.
* public will mount read-only.
* private will mount read-write.
* AutoFS mounts on access rather than permanently at boot.

質問 5：
Create a group named ops, create user sara, and add sara to the supplementary group ops.
正解：
See the solution below in Explanation.
Explanation:
Solution:
groupadd ops
useradd sara
usermod -aG ops sara
id sara
Detailed Explanation:
* groupadd creates the group.
* useradd creates the user.
* usermod -aG adds the user to a supplementary group without removing existing memberships.
* id sara confirms the result.

質問 6：
Create a systemd service named backup-now.service that runs /usr/local/bin/backup-now.sh.
正解：
See the solution below in Explanation.
Explanation:
Solution:
Create the script:
mkdir -p /usr/local/bin
cat > /usr/local/bin/backup-now.sh < < 'EOF'
#!/bin/bash
tar -czf /root/etc-$(date +%F).tar.gz /etc
EOF
chmod +x /usr/local/bin/backup-now.sh
Create the unit file:
cat > /etc/systemd/system/backup-now.service < < 'EOF'
[Unit]
Description=Run manual etc backup
[Service]
Type=oneshot
ExecStart=/usr/local/bin/backup-now.sh
[Install]
WantedBy=multi-user.target
EOF
Reload and test:
systemctl daemon-reload
systemctl start backup-now.service
systemctl status backup-now.service
Detailed Explanation:
* Type=oneshot is correct for a task that runs and exits.
* ExecStart points to the script.
* systemctl daemon-reload is required after adding a new unit file.
* RHEL 10 systemd documentation covers manual unit creation and management. ( Red Hat
Documentation )

質問 7：
Create /share/projects, make alex the owner, and configure the sticky bit so users cannot delete each other's files.
正解：
See the solution below in Explanation.
Explanation:
Solution:
mkdir -p /share/projects
chown alex /share/projects/
chmod a+rwx,+t /share/projects/
ls -ld /share/projects/
Detailed Explanation:
* chmod a+rwx gives read, write, and execute to everyone.
* +t sets the sticky bit.
* Sticky bit on a shared directory means users can create files, but only the file owner, directory owner, or
root can delete them.
* This is the same model used on /tmp.