This page is edited from the 1cmdfaq.txt faq-file contained in
my tscmd.zip
command line interface (CLI) collection. That zipped file has much
additional material, including a number of detached .cmd script
files. It is recommended that you also get the zipped version as a
companion.
Please see "
The Description and
the Index page" for the conditions of usage and other such
information.
158} Why won't the statements within my if condition work properly?
There are several examples throughout the 1CMDFAQ.TXT FAQ about for
loops which require delayed expansion. The need for delayed expansion is,
however, not limited to
for-loops.
Below is an artificial example reminding the reader that the
operations within an if statement have the same feature:
@echo off & setlocal enableextensions
set par1=%1
if "%par1%"=="a" (
set par2=%2
echo
%par2
%
)
endlocal & goto :EOF
The output will be
C:\_D\TEST>cmdfaq a b c d
ECHO is off.
However, written appropriately
@echo off & setlocal enableextensions
enabledelayedexpansion
set par1=%1
if "%par1%"=="a" (
set par2=%2
echo
!par2
!
)
endlocal & goto :EOF
The output will be what one rather would want:
C:\_D\TEST>cmdfaq a b c d
b
The latter could, of course, also be written as
@echo off & setlocal enableextensions disabledelayedexpansion
set par1=%1
if not "%par1%"=="a" goto next1
set par2=%2
echo %par2%
:next1
endlocal & goto :EOF
Also see
item38.
Next, consider a practical example which involves multiple related
aspects including for-loops, if-statements and testing errorlevels.
The task is to test the integrity of a set of .zip files. The
following code will tell whether they all pass, or if any number of
them includes errors.
@echo off & setlocal enableextensions enabledelayedexpansion
set unzipProg=C:\_F\TOOLS\PKUNZIP.EXE
set error_=
for %%f in ("C:\_E\TSZIP\*.ZIP") do (
"%unzipProg%" -t "%%f">nul
if !errorlevel! GTR 0 set error_=true)
if defined error_ (
echo Error^(s^) in at least one of the browsed .zip files
) else (
echo No errors in the browsed .zip files)
endlocal & goto :EOF
Assorted NT/2000/XP/.. CMD.EXE Script Tricks
