A.The batch command will run multiple times.
The at command will only run once.

B.The batch command will run when system load is low.
The at command runs at a specific time.

C.The at command reads commands from standard input.
The batch command requires a command line argument.

D.The at command e-mails results to the user.
The batch command logs results to syslog.

A.By a fixed UUID that is defined in the X11 configuration file.

B.By a display name like: 1.

C.By the name of the user that runs the X server like x11:bob.

D.By a device name like /dev/X11/xservers/1.

E.By a unique IPv6 address from the fe80::/64subnet.

A.until

B.loop

C.while

D.for

A.ifconfig unset default

B.route del default

C.ip route del default

D.sysctl ipv4.default_gw=0

E.netstat -r default