How to set the value of an environment variable to the output of a command in a WIndows batch file?

Question

How can I set an environment variable to the output of a command in a Windows batch file? The command will return a single value of around 32 characters (e.g. type myfile.txt).

Answer 1

Try running these commands:

for /f "delims=" %a in ('mybatchfile.bat') do @set myenvvar=%a
echo %myenvvar%

Answer 2

Temporarily:

for /f "delims=" %a in ('command to run') do @set example_environment_variable=%a

Permanently:

for /f "delims=" %a in ('command to run') do @setx example_environment_variable=%a

---

Sidenote, set sets it just for this command process/window, but setx sets it for the whole user/system.

Answer 3

Alternatively:

for /f "usebackq delims==" %v in (`echo new_value`) do set new_var=%v 

Why would somebody want to use this version?

According to for /? help, one may want to use it when dealing with double quotes in the file names (as a matter of fact, that's how I ended up here):

usebackq        - specifies that the new semantics are in force,
                  where a back quoted string is executed as a
                  command and a single quoted string is a
                  literal string command and allows the use of
                  double quotes to quote file names in
                  file-set.

[...]

Finally, you can use the FOR /F command to parse the output of a
command.  You do this by making the file-set between the
parenthesis a back quoted string.  It will be treated as a command
line, which is passed to a child CMD.EXE and the output is captured
into memory and parsed as if it was a file.  So the following
example:

  FOR /F "usebackq delims==" %i IN (`set`) DO @echo %i

would enumerate the environment variable names in the current
environment.