who and write

Similar to wall, messages can be sent to an individual user using write. First, you need to know who that individual user is (another straightforward command–amazing).

emmett@splinter:~$ who
emmett   tty7         2018-03-08 12:18 (:0)
hatice   pts/2        2018-03-07 09:40 (10.144.120.1)
hatice   pts/18       2018-03-07 09:52 (10.144.120.1)
hatice   pts/9        2018-03-08 10:49 (10.144.120.1)
hatice   pts/1        2018-03-08 14:42 (10.144.120.1)
emmett   pts/20       2018-03-09 09:53 (10.144.120.22)
emmett   pts/21       2018-03-09 09:53 (10.144.120.22)

In the example, 6 Terminal windows are open on splinter. The user hatice has 4 windows open, while emmett has 3 open, one of which is through an ssh session. The dates and times specify when the window was first opened. Now that we know who has windows open, and what they are (shown in the second column), we can send a message to any of those windows. I chose to write a message to myself. This is what the writing terminal looks like.

emmett@splinter:~$ write emmett pts/20
Hi pal! Nice you see that I can talk to you via ssh!
I\'m glad I can take over your Terminal. Now get back to work!

Like before, I can use enter for line breaks, and I send by using Cntrl+D (and not command if on a Mac). This is what the receiving Terminal looks like (it literally takes over so you can’t do work).

emmett@splinter:~$
Message from emmett@splinter on pts/21 at 09:54 ...
Hi pal! Nice you see that I can talk to you via ssh!
I\'m glad I can take over your Terminal. Now get back to work!
EOF

After the EOF (End-of-File), you can hit enter to get the command prompt back.