See the solution below in Explanation.
Explanation:
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.

Solution:
[root@node1 ~]# systemctl status crond
[root@node1 ~]# systemctl enable crond
[root@node1 ~]# crontab -e -u harry
23 14 * * * /usr/bin/echo hello
# Verification
[root@node1 ~]# crontab -l -u harry

See the solution below in Explanation.
Explanation:
Solution:
systemctl enable --now fstrim.timer
systemctl status fstrim.timer
Detailed Explanation:
* fstrim.timer schedules discard of unused blocks.
* This is useful on SSD-backed storage and thin-provisioned environments.
* RHEL 10 storage documentation explicitly documents enabling fstrim.timer. ( Red Hat Documentation )

Explanation/Reference:
Solution:
su - natasha
vim .bashrc
alias rhcsa='ehco This is a rhcsa'
source .bashrc
rhcsa

See the solution below in Explanation.
Explanation:
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.