Learning to use the bash command line

[Vince53]

Okay, this stupid but harmless command actually works

sudo apt install sl

After it is installed, type sl

 

[skalle]

Okay, this stupid but harmless command actually works

sudo apt install sl

After it is installed, type sl

That's the reverse of ls, which prints the contents of the current directory. Just a nice reminder that you've made a typo.

 

[Qyöt27]

That's the reverse of ls, which prints the contents of the current directory. Just a nice reminder that you've made a typo.

Actually...

 

[Vince53]

Right you are, Skalle. The author actually explained that it is a friendly way of showing you where you made a typo in typing out a command line instruction.

 

[skalle]

Actually...

I don't get it. I know what it does.

When I write my own OS, it's going to harass you if it thinks you messed up. No nice pretty choo-choos!

 

[Vince53]

Not really, Skalle. If you accidentally type sl instead of ls, the program only runs for a couple of seconds, and it shows you where your mistake is (by letting you know that you typed sl instead of ls).

 

[skalle]

?

 

[Vince53]

I need to clarify:

Bash is not an operating system. It is a "shell" whose primary purpose is to help developers write programs. However, people have written various Bash programs that you can download for free, using the sudo command. But Bash actually includes some built-in programs. Here are three of them:

cal prints this month's calendar with today's date.

factor (number) breaks any number down into its prime factors. For those who forgot your high school math, a prime number can only be divided by itself and 1. Type factor 4 into the command line, and it will tell you 4: 2 2. Since 2 is a prime number, it cannot go lower than 2. No matter how large the number, the factor command will break it down into prime numbers. Factor 456 will tell you that 2 2 2 3 19 are the prime factors of 456.

for i in {1..9}; do for j in $(seq 1 $i); do echo -ne $i×$j=$((i*j))\\t;done; echo;done This prints the times tables up to 9. You can replace the numbers 1 and 9 with other numbers. I actually typed in 111 and 999, and it gave me all the times tables for them.