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.
29} How do I drop the first two characters of a string, and so on?
In CMD.EXE scripts dropping the first two characters is very simple:
@echo off & setlocal enableextensions
setlocal enableextensions
set test_=This is a test
echo %test_:~2%
endlocal & goto :EOF
The output is
is is a test
As we have seen, the base syntax for extracting a substring is
%var_:Start,Count% where the first
character is designated
0 (zero)
not one. Thus
@echo off & setlocal enableextensions
setlocal enableextensions
set test_=This_is_a_test
echo %test_:~2,5%
endlocal & goto :EOF
gives
is_is
Now, how about dropping the LAST two characters?
@echo off & setlocal enableextensions
setlocal enableextensions
set test_=This_is_a_test
echo %test_:~0,-2%
endlocal & goto :EOF
gives
This_is_a_te
The above
drops the last two characters,
but reversing how does one
get them?
@echo off & setlocal enableextensions
setlocal enableextensions
set test_=This is a test
echo %test_:~-2%
endlocal & goto :EOF
gives
st
Obviously there are more potential combinations, but this is how the
basics go. For more see
CMD1DEMO.CMD "
A CMD syntax selection demo". Also see
Item #44.
For the sake of comparison let's demonstrate solving dropping the
first two characters with a Visual Basic aided script (VBScript):
@echo off & setlocal enableextensions
setlocal enableextensions
set test_=This is a test
echo %test_%
>"%temp%\tmp$$$.vbs" echo WScript.Echo Mid("%test_%",
3)
for /f "tokens=* delims=" %%a in (
'cscript //nologo "%temp%\tmp$$$.vbs"') do set test_=%%a
for %%f in ("%temp%\tmp$$$.vbs") do if exist %%f del %%f
echo %test_%
endlocal & goto :EOF
The output is
C:\_D\TEST>cmdfaq
This is a test
is is a test
With
G(nu)AWK:
@echo off & setlocal enableextensions
setlocal enableextensions
set test_=This is a test
echo %test_%
gawk 'BEGIN{printf "set test_=%%s\n",substr("%test_%",3)}'>"%temp%\tmp$$$.cmd"
for %%c in (call del) do %%c "%temp%\tmp$$$.cmd"
echo %test_%
endlocal & goto :EOF
@echo off & setlocal enableextensions
setlocal enableextensions
rem The same with GnuWin32 gawk (let's call it unxgawk)
set test_=This is a test
echo %test_%
unxgawk "BEGIN{printf \"set test_=%%s\n\",substr(\"%test_%\",3)}"^
>"%temp%\tmp$$$.cmd"
for %%c in (call del) do %%c "%temp%\tmp$$$.cmd"
echo %test_%
endlocal & goto :EOF
Assorted NT/2000/XP/.. CMD.EXE Script Tricks
