What are the ` symbols used for?
python3.4 `which ptpython`
Backticks are used in bash to write some executable command, the result of which will be used in the script.
Например попробуйте: echo `whoami` и echo 'whoami'
The first option will execute the whoami command and print its result (the name of the current user), the second option will simply print the string "whoami".