How many times do we make a mistake by typing some command in the terminal? ... I don't know about you, but I have a bad habit of making mistakes several times, either because I type in the terminal and at the same time I am attending to the person next to me, or because it is simply such a long line that I am wrong.
The problem with all this is to retype the line, or in any case to press the arriba on the keyboard, scroll to the mistake we made, fix it and then press [Enter], either way it can be a bit of a nuisance 
Well, I'll now show you how to correct any mistakes you made when you inserted the previous command, but without even having to type or display that previous command in the terminal again 
Sounds like magic right… fixing a misspelled command without even looking at it or typing it again? …yes 
For example, I show you the trick without much complication. To access the / var / log / folder in a terminal it would be: cd / var / log or not? well let's open a terminal and misspell that line, let's say:
cd /var/lgo/
As you can see, I changed log to lgo, which means I wrote one letter instead of another, which is a very common mistake 
This obviously won't work, it will tell you that the / var / lgo / directory doesn't exist, which is true. Now in that same terminal write:
^lgo^log^
And press [enter], you will see how they magically accessed the correct directory LOL !!
What does this mean? 0_oU ...
Simple, we put first what is the error (lgo) and then we put why we want to change it (log), this entire line starts with a character ^ and ends the same with the same character, in turn this character is the one who divides the error from what is correct to put.
Simply put, they put a ^, then they put where they made a mistake, they put another ^ which will be the division, then they put what they want to be correct and finish with another ^. Simple right? 
I know that some of you will still prefer to press [Up] and fix the error on the command line, others may use this tip, the truth is that I'm sure you all find it interesting... and if not, well, at least you've learned a new trick 
regards