i tried running "who am i" command but there is no output,but my professor has "howard pts/2 2017-05-29 10:43 (:0)"
2.when i run whoami command its shows as tty not pts/
Thank you

One command is $(whoami), then other is $(who) with parameters "am i".

$ whoami

$ who am i

BUT "WHOAMI" is giving me the username, but no output for "who am i"

There is a Linux command who. Who am i is not a valid form of that command, as am i are not valid arguments for who. Consequently, who am i is not a valid command. See man who for more about the who command.

(The who command is completely different from the whoami command.)

To put it another way, who am i asks as question that Linux cannot interpret, so, in your case at least, no answer is provided. It understands the who, but it doesn't understand the am i.

It's sort of like asking, "What's your favorite make of automobile: Dell, Lenovo, or Zareason?"

(I'm mildly surprised you didn't get something like I got:

My Slackware system just ignored the am i, knowing they weren't valid, and responded as if the command had been a simple who.)

Indeed, we were talking about this at my LUG dinner tonight. Learning the command line is like learning a new language. It has nouns, verbs, and modifiers (nouns=files and folders, verbs=commands, modifiers=arguments to commands) and especially it has a very strict syntax. A human being can usually understand what you mean if you misspell a word or use the wrong tense of a verb; a computer cannot.

The darn things xpect you to speek to them correctly, just as crossword puszles expect you to splet words rite.

The man page for whoami basically says that it is equivalent to $(id -un)

$ id -un
$ whoami

versus something like

$ who -a

or

$ id

1 members found this post helpful.

Thanks, Shadow_7, I learned something. That makes my day.

man who on my ubuntu tells:
ARG1 ARG2 can be: am I, or mom likes or anything else, and is identical to -m

1 members found this post helpful.

Thanks. A nice tidbit!

I see that who without additional arguments returns all logged in users; who -m seems to return the user that invoked who.

From the man page:

With that switch, it performs the same function as whoami, but returns a bit more information (pts, etc.)

Not exactly. 'whoami' prints the username for the effective userid, 'who am i' prints the user associated with stdin. For example, if you use 'su' or 'sudo' to switch to a different user, 'whoami' and 'who am i' will be different. They distinguish between who you logged in as (who am i) vs. the user you are right now (whoami).

WORKAROUND:
This works as replacement from and may look like what you are looking for.

Explanation:

On many systems "who am i" is equivalent to "who -m". (I believe this works for most Linux but not all Unix? To be confirmed…)
The problem here is that with some terminals, "who -m" returns nothing!

Example #1 run from a xfce4-terminal on Mint 18+, after "sudo su"
but
Example #2 from a gnome-terminal (same computer, same commands)
This seems to be a consequence of gnome-terminal not adding utmp entries…