How to substitute variable contents in a Windows batch file

Question

I\'m writing a simple script to substitute text in an environment variable with other text. The trouble I get is with the substituted or substituted text being pulled from o

Answer 1

Use CALL. Put the following in a batch script and run it:

set a=The fat cat
set b=fat
set c=thin

REM To replace "%b%" with "%c%" in "%a%", we can do:
call set a=%%a:%b%^=%c%%%
echo %a%
pause

As stated here, we use the fact that:

CALL internal_cmd

...

internal_cmd Run an internal command, first expanding any variables in the argument.

In our case internal_cmd is initially set a=%%a:%b%^=%c%%%.

After expansion internal_cmd becomes set a=%a:fat=thin%.

Thus, in our case running

call set a=%%a:%b%^=%c%%%

is equivalent to running:

set a=%a:fat=thin%.