if

if (condition)
      command
[else]
      [command]

If condition is true, do command(s), otherwise do command in else clause. Condition can be an expression using any of the relational operators <, <=, ==, !=, >=, or >, as well as the pattern-matching operator ~ (e.g., "if ($1 ~ /[Aa].*/)"). A series of commands must be put within braces.