Command Grouping

Command grouping allows you to logically group a set of commands together 
by enclosing them in parentheses.  The parentheses are similar in function 
to the BEGIN and END block statements in some programming languages. 

There are two primary uses for command grouping.  One is to execute 
multiple commands in a place where normally only a single command is 
allowed.  For example, suppose you want to execute two different REN 
commands in all subdirectories of your hard disk.  You could do it like 
this: 

        [c:\] global ren *.wx1 *.wxo
        [c:\] global ren *.tx1 *.txo

But with command grouping you can do the same thing in one command (enter 
this on one line): 

        [c:\]global (ren *.wx1 *.wxo & ren *.tx1 *.txo)

The two REN commands enclosed in the parentheses appear to GLOBAL as if 
they were a single command, so both commands are executed for every 
directory, but the directories are only scanned once, not twice. 

This kind of command grouping is most useful with the EXCEPT, FOR, GLOBAL, 
and IF commands.  When you use this approach in a batch file you must 
either place all of the commands in the group on one line, or place the 
opening parenthesis at the end of a line and place the commands on 
subsequent lines.  For example, the first two of these sequences will work 
properly, but the third will not: 

        for %f in (1 2 3) (echo hello %f & echo goodbye %f)
        for %f in (1 2 3) (
                echo hello %f
                echo goodbye %f
        )
        for %f in (1 2 3) (echo hello %f
        echo goodbye %f)

The second common use of command grouping is to redirect input or output 
for several commands without repeatedly using the redirection symbols. 
 For example, consider the following batch file fragment which uses the 
ECHO command to create a file (with >), and to append to the file (with 
>>): 

        echo Data files %_date > filelist
        dir *.dat >> filelist
        echo. >> filelist
        echo Text files %_date >> filelist
        dir *.txt >> filelist

Using command grouping, these commands can be written much more simply. 
 Enter this example on one line: 

        (echo Data files %_date & dir *.dat & echo. & echo Text files
        %_date & dir *.txt) > filelist

The redirection, which appears outside the parentheses, applies to all the 
commands within the parentheses.  Because the redirection is performed 
only once, the commands will run slightly faster than if each command was 
entered separately.  The same approach can be used for input redirection 
and for piping. 

You can also use command grouping in a batch file or at the prompt to 
split commands over several lines.  This last example is like the 
redirection example above, but is entered at the prompt.  Note the "More?" 
prompt after each incomplete line.  None of the commands are executed 
until the command group is completed with the closing parenthesis.  This 
example does not have to be entered on one line: 

        [c:\] (echo Data files %_date
        More? dir *.dat
        More? echo.
        More? echo Text files %_date
        More? dir *.txt) > filelist
        [c:\]

A group of commands in parentheses is like a long command line.  The total 
length of the group may not exceed 2,047 characters, whether the commands 
are entered from the prompt, an alias, or a batch file.  The limit 
includes the space required to expand aliases and environment variables 
used within the group.  In addition, each line you type at the normal 
prompt or the More? prompt, and each individual command within the line, 
must meet the usual length limit of 1,023 characters.