Bat If Command common judgment Introduction _dos/bat

If command

If the condition is judged to be in compliance with the stipulated conditions, it is decided to execute different commands.

There are three different formats:

1), if "parameter" = = "string" command to be executed

If the parameter is equal to the specified string, the condition is set, the command is run, or the next sentence is run. (note is two equals)

If "%1" = = "A" format a:
if {%1}=={} goto noparms
if {%2}=={} goto noparms

2), if exist filename to execute command

If you have the specified file, the condition is set, run the command, or run the next sentence.
such as if exist Config.sys edit Config.sys

3), if errorlevel/if not errorlevel number of commands to be executed

If the return code equals the specified number, the condition is set, the command is run, or the next sentence is run.

if errorlevel 2 goto x2

DOS program will return a number to DOS, called error code ERRORLEVEL or return code, the common return code is 0, 1.