How to store the hostname in a variable in a .bat file?

I usually read command output in to variables using the FOR command as it saves having to create temporary files. For example:

FOR /F "usebackq" %i IN (`hostname`) DO SET MYVAR=%i

Note, the above statement will work on the command line but not in a batch file. To use it in batch file escape the % in the FOR statement by putting them twice:

FOR /F "usebackq" %%i IN (`hostname`) DO SET MYVAR=%%i
ECHO %MYVAR%

There's a lot more you can do with FOR. For more details just type HELP FOR at command prompt.