EFI Shell commands -- IF(在一個特定的狀況去執行一個或多個指令)

Executes one or more commands in specified conditions.

IF [NOT] EXIST file THEN
    command [arguments]
[ELSE
    command [arguments]]
ENDIF


IF [NOT] string1 == string2 THEN
    command [arguments]
    [command [arguments]]
    ...
[ELSE
    command [arguments]
    [command [arguments]]
    ...]
ENDIF


    EXIST file            - TRUE if file exists in the directory
    string1 == string2    - TRUE if the two stings are same

Note:
    1. The IF command is only available in batch script files.
    2. If condition is TRUE, commands between IF and ELSE will be
       executed.
    3. If condition is FALSE but keyword 'NOT' is not prefixed, commands
       between ELSE and ENDIF will also be executed.

Examples:
    #
    #  Example script for "if" command
    #
    if exist fs0:\myscript.sc then
    myscript myarg1 myarg2
    endif
    if %myvar% == runboth then
    myscript1
    myscript2
    endif