Quotes in shell programming

程序设计

Every thing is shell scripts is string, so quoting is extremely and unfortunately important in shell programming.

Type of quoting

• '': Remove any special mean of character, except '.
• "": Allow $ substitution.
• ``: Legacy command substitution, use $() instead.

Effects

• Preserve unescaped metacharacters.
• Prevent field splitting and glob pattern characters.
• Expand argument lists.
  ${array[@]} expands to a list of words.