title: Continue running program until user type Ctrl + a
body: <p>I'm practicing C programming for Linux for an exam.
  I don't know how to exit the program when user press Ctrl + a ( not Ctrl+c )
  For example, looping something until user press Ctrl+a
  Could anyone tell me how to check Ctrl+a input?</p>
  
  <p>Notes: I'm using 'gcc' and run output with './a.out'</p>
  
  <p>Thanks in advance for everyone!</p>