Question

I have a build.bat file which uses %1 internally… so you might call:

build 1.23

I wanted it to read the parameter from a separate file, so I tried putting “1.23” in version.txt and doing:

build < version.txt

But it doesn’t work. Isn’t this how piping works? Is what I want possible and if so how?

Answer 1

The FOR command in DOS has a form which parses files and assigns the tokens it finds to variables, which can then be used as arguments to other batch files. Assuming version.txt contains the single line “1.23”, this batch file will open it, assign 1.23 to the variable, then call your original batch file, passing the variable’s value as a command-line argument.

@echo off
for /f %%i in (version.txt) do call build.bat %%i

If version.txt contains more than one line, build.bat is called once for each line. Type help for at a DOS prompt to see what other features you might be able to use.