RedHat EX200 - Red Hat Certified System Administrator - RHCSARHEL 10

Solution:

systemctl set-default multi-user.target

systemctl get-default

Detailed Explanation:

set-default changes the boot target persistently.

get-default verifies the result.

multi-user.target is the standard non-graphical multi-user boot target.

Solution:

dnf install -y autofs

mkdir -p /shares

echo "/shares /etc/auto.shares" > > /etc/auto.master

echo "projects -fstype=nfs,rw server1:/srv/nfs/projects" > /etc/auto.shares

systemctl enable --now autofs

ls /shares/projects

Detailed Explanation:

/etc/auto.master defines the main map.

/etc/auto.shares defines the indirect mount entry.

The mount happens on demand when /shares/projects is accessed.

RHEL 10 file-system documentation includes AutoFS for on-demand mounts. ( Red Hat Documentation )

Solution:

mkdir -p /root/d1

find /usr/local -type f -size +3k -size -5k -exec cp -rvf {} /root/d1/ \;

chmod g+s /root/d1

ls -ld /root/d1

Detailed Explanation:

-size +3k means greater than 3 KB.

-size -5k means less than 5 KB.

chmod g+s sets the SGID bit on the directory.

SGID on a directory causes new files created there to inherit the directory’s group.

Solution:

Open the firewall port and HTTP service:

firewall-cmd --permanent --add-port=82/tcp

firewall-cmd --permanent --add-service=http

firewall-cmd --reload

Add SELinux port labeling:

semanage port -a -t http_port_t -p tcp 82

Detailed Explanation:

firewall-cmd --permanent makes the change persistent.

--add-port=82/tcp opens the custom TCP port.

--add-service=http keeps standard HTTP allowed too.

SELinux blocks services on unexpected ports unless the port is labeled correctly.

http_port_t tells SELinux that port 82 is valid for web services.

Solution:

Reboot the server.

At the GRUB menu, highlight the kernel entry and press e.

Find the line starting with linux.

Append:

systemd.unit=emergency.target

Press Ctrl+x to boot.

Detailed Explanation:

This changes the boot target only for the current boot.

Emergency mode is useful for rescue and maintenance tasks.

Red Hat’s RHEL 10 systemd guidance documents booting with systemd.unit= < name > .target from GRUB. ( Red Hat Documentation )

Solution:

Partition the disk:

fdisk /dev/sdb

Inside fdisk:

n = new partition

p = primary

1 = partition number

accept defaults

size +700M

t = change type

set Linux LVM type

w = write changes

Create the physical volume:

pvcreate /dev/sdb1

Create the volume group:

vgcreate vg_data /dev/sdb1

Create the logical volume:

lvcreate -L 500M -n lv_data vg_data

Create the filesystem:

mkfs.xfs /dev/vg_data/lv_data

Detailed Explanation:

The lab specifies a 700 MB partition and a 500 MB logical volume.

pvcreate initializes the partition for LVM.

vgcreate builds the storage pool.

lvcreate allocates space from the volume group.

mkfs.xfs creates the filesystem, which is standard on RHEL.

Solution:

groupadd admin

mkdir -p /common/admin

chgrp admin /common/admin

chmod 2770 /common/admin

Detailed Explanation:

groupadd admin creates the group.

chgrp admin assigns the group ownership.

2770 means:

2 = SGID

7 = owner rwx

7 = group rwx

0 = others no access

This is a standard shared group-admin directory design.

Solution:

tar -zvcf /root/etc_backup.tar.gz /etc

file /root/etc_backup.tar.gz

Detailed Explanation:

tar creates the archive.

-z uses gzip compression.

-v is verbose.

-c creates the archive.

-f names the output file.

file confirms the resulting archive type.

Solution:

Read-only access:

setfacl -m u:john:r-- /share/dev

Read-write access:

setfacl -m u:john:rw- /share/dev

Remove ACL permissions:

setfacl -m u:john:--- /share/dev

Detailed Explanation:

setfacl -m modifies the ACL.

u:john:r-- grants read only.

u:john:rw- grants read and write.

u:john:--- effectively removes access for that ACL entry.

ACLs are used when standard owner/group/other permissions are not enough.