RHCSA Linux System Administration Flashcards

Which command schedules a one-time job to run at 2:30 PM today using the 'at' utility?

Answer: at 14:30

The 'at' command accepts 24-hour time directly; after entering the command, you type your job and press Ctrl+D.

What does the 'ss -tulnp' command display?

Answer: TCP and UDP listening sockets with process info and no DNS resolution

-t=TCP, -u=UDP, -l=listening, -n=no DNS, -p=process; combined they show listening network sockets with PIDs.

A filesystem mounted at /data is running low on space. The underlying LV is in vg0. Which command extends it by 10GB?

Answer: lvextend -L +10G /dev/vg0/data && xfs_growfs /data

lvextend grows the LV and xfs_growfs expands the XFS filesystem online to fill the new space.

Which file should be edited to set a system-wide default umask for all users?

Answer: /etc/profile

/etc/profile is sourced for all login shells and is the standard place to set a system-wide umask.

How do you set the hostname to 'webserver01.example.com' persistently using a single command?

Answer: hostnamectl set-hostname webserver01.example.com

hostnamectl set-hostname updates /etc/hostname and applies the change immediately and persistently.

Which command lists all enabled systemd services that start at boot in the default target?

Answer: systemctl list-unit-files --type=service --state=enabled

--state=enabled filters unit files to only show those enabled to start automatically.

What is the correct NFS mount entry in /etc/fstab to mount 192.168.1.10:/exports/data at /mnt/data with read-write and auto-mount?

Answer: 192.168.1.10:/exports/data /mnt/data nfs rw,_netdev 0 0

_netdev tells systemd to mount after network is available, which is required for network filesystems.