17. After a CentOS 7 script is completed and saved, which commands are required to execute the script? (Choose all that apply.) a. createlist more b. chmod 755 createlist.sh c. /createlist.sh d. vim createlist.sh 18. In CentOS 7 scripts, which commands are required? (Choose all that apply.) # ! /bin/bash a. b. head c. tail d. exit 0 19. In CentOS 7 scripts, which commands enable multiple executions of a set of instruc- tions until a condition is met? (Choose all that apply.) a. circle b. for c. while d. loop 20. Which of the following file extensions can you use on scripts in CentOS 7? a. .exe b. cmd c. .bat d. sh