"CLS" Equivalent in BASH?

Short Answer

clear && clear

or

tput reset

Other Ways

Here are all the ways you can clear the terminal screen in Unix:

clear               # only clear visible screen
clear && clear      # clear buffer as well
tput clear          # same as clear but by sending escape seq
reset               # clear + reset internal terminal state + 1sec delay
tput reset          # same as reset but without 1sec delay
stty sane           # don't clear screen but reset some terminal options
echo -e "\033c"     # same as tput reset but hardcoded escape seq
printf "\033c"      # same as tput reset but hardcoded escape seq
setterm -reset      # same as tput reset, setterm has friendlier commands

Long Answer

The clear command only clears the visible screen but not the buffer so you can do Shift+PageUp to scroll up in the terminal and still view previous outputs. If you want to get same result as cls then do clear twice like clear && clear.

Another related command is reset which (I believe) resets the internal state of the terminal program. Unfortunately, this command includes 1 second of delay to support really old terminals. So if you are not ok with that kind of delay then use tput reset which seems to do same thing as reset minus the delay.

But what does tput do? In Unix, you can send terminal all kinds of ASCII character sequences which are interpreted as commands by the terminal. This allows you to do funky things like blink or color the text or turn off echo (during password typing) or set terminal options or do clear or reset. This you can send by tput clear or tput reset. The clear and reset command are equivalent but they run from the binaries that comes with your distro and may do additional stuff. The setterm -reset is similar to tput reset. Setting terminal using setterm is usually better because unlike tput it has more readable options in general case however we here use tput because it's smaller in length :).

You might have also seen people using things like echo -e "\033c" or printf "\033c" which is equivalent to tput reset but the escape sequence is now hard coded. The tput looks up terminal properties and uses the right escape sequence.

Another related command is stty sane which actually doesn't do any screen clearing but it sets many of the terminal options to defaults so if your terminal looks garbled or if terminal stays blank when you type (for example, because you printed binary file to terminal with escape sequence to turn off echo) then this command might help. For extreme garbled terminal cases, you can use all of the available resetting techniques in the sequence. I've alias like this for such occasions:

alias cls='tput reset'
alias clshard='reset; stty sane; tput rs1; setterm -reset; tput reset'

Related

What's the equivalent of the “cls” command from Windows/DOS?

What commands can I use to reset and clear my terminal?

In ~/.bashrc, the perfect cls is:

cls () {
    printf -- '%b' '\033c'
    return $?
}

The clear command works for me.

But I personally find it impractical, because, for me, it clears the scrollback permanently and irreversibly. However, often I want just to insert some "marker"/"separator" into the scrollback, in order to be able to visually distinguish the "recent scrollback" from the "too old scrollback" (but sometimes ability to see the "too old scrollback" would be still useful). So I use something like:

yes '' | head -n100

That inserts 100 empty lines into the scrollback. (Inspired by this answer. You can vary the number of lines, of course.)