Syntax, commands, control structures and conventions for Windows batch files. Handy if you want to automate something on your Windows machine. Although, to be honest, the last time I did so seriously was 20 years ago during my civil service.
| filename |
Batch files end with .BAT there is no magical string
like in Un*x batch file commands are case insensitive |
| comments |
rem at line start is a comment line |
| in/output redirection |
cmd <in-file >out-file-new
cmd >>out-file-append
stderr cannot be redirected, always goes to screen. |
| parameters |
%1 to %9 arguments number 1 to 9 given to the batch
file %* all arguments given to the batch file (max.
9) |
| environment variables |
%varname% |
| conditions |
if [not] "string1" == "string2" command Enclose vars
and strings in "". Idiom for empty check:
if "%var%" == "" command ("" needed for empty
string).
if [not] exist filename command
if errorlevel 1 would test for any abnormal exit.
errorlevel is the number the last program executed returned. The
condition is true if the number is >= the errorlevel. Normal
exit returns 0. |
| logical operators |
&&execute only when last prog returned
ok
||execute only when last prog returned error |
| skript loops |
for %% var in ( group ) do command
[params]
var wird zu jedem in group angegebenen dateinamen, eg for %%f
in (*.*) do type %%f |
| skript jumps |
goto mark The target mark itself has to be prepended
with : so NT can skip it during execution.
:mark |
| skript chaining |
call blah.bat calls another batch like a subroutine,
i.e. the current batch's execution is resumed after the other one
ends. Recursion possible. |
| skript messages |
echo [on|off][message]
@ at line start suppress showing of any single line
@echo off showing of any line (including this). Echo with
message prints message. |
| getting user input for skripts |
pause[message] halts until any key pressed. |
| ... |
shift shifts the params in a batch one down, e.g.
%9 to %8. %0 is lost and if there
were more than 10 params, the current number 11 becomes
%9. Example loop with shift
:next
if "%0" == "" goto end
type %0
shift
goto next
:end
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