A.rmdir "~/\dir"

B.rmdir ~/\\dir

C.rmdir ~/\dir

D.rmdir '~/\dir'

E.rmdir ~/'dir'

A.It sets up environment variables for applications.

B.It allows disks to be mounted remotely.

C.It runs a command as a process in a subshell.

D.It shares NFS partitions for use by other systems on the network.

E.It makes the command history available to subshells.

A.grep -v fred data_file

B.grep '[f]red' data_file

C.egrep fred data_file

D.grep '[Ff]red' data_file

E.grep -i fred data_file

A.Port 23 is the well-known port for the system login services which are encrypted when the user runs the starttls command in his login shell.

B.Port 23 is the well known port for the telnet service which is a plain text protocol that should no longer be used.

C.Port 23 is the well known port for the rlogin service which is SSL secured by default.

D.Port 23 is the well known port for the SSH service which provides secure logins.

A.foo

B.tee bar

C.foo bar

D.cat

E.bar