PicoCTF - useless

There's an interesting script in the user's home directory.

The work computer is running SSH. We've been given a script that performs some basic calculations, explores the script, and finds a flag.

Open up the terminal and connect with SSH to the server.

ssh picoplayer@saturn.picoctf.net -p 51135

Enter the provided password. Verify that you are inside the home directory and see the contents of that directory.

pwd
ls
cat useless

#!/bin/bash
# Basic mathematical operations via command-line arguments

if [ $# != 3 ]
then
  echo "Read the code first"
else
	if [[ "$1" == "add" ]]
	then 
	  sum=$(( $2 + $3 ))
	  echo "The Sum is: $sum"  

	elif [[ "$1" == "sub" ]]
	then 
	  sub=$(( $2 - $3 ))
	  echo "The Substract is: $sub" 

	elif [[ "$1" == "div" ]]
	then 
	  div=$(( $2 / $3 ))
	  echo "The quotient is: $div" 

	elif [[ "$1" == "mul" ]]
	then
	  mul=$(( $2 * $3 ))
	  echo "The product is: $mul" 

	else
	  echo "Read the manual"
	 
	fi
fi

man useless

This is all that was needed. You can find the flag under 'Authors' at the end of the man page. Nice one, you've got the flag!