[bash] [ test

Why do I need to quote variable for if

What is the difference between [[ $a == z* ]] and [ $a == z* ]?

Bash ADV

• 0xff or o12 does not evaluated in [ command
• always quote variables in [ command
• never use the -a or -o operator (use several [ commands and the && and || shell operators)
• The whole [[ ... ]] construct makes up a command.