For Command

From Luke Jackson

Summary

Usage

Runs a specified command for each file in a set of files.

FOR %variable IN (set) DO command [command-parameters]

 %variable  Specifies a single letter replaceable parameter.
 (set)      Specifies a set of one or more files.  Wildcards may be used.
 command    Specifies the command to carry out for each file.
 command-parameters
            Specifies parameters or switches for the specified command.

To use the FOR command in a batch program, specify %%variable instead of %variable. Variable names are case sensitive, so %i is different from %I.

If Command Extensions are enabled, the following additional forms of the FOR command are supported:

FOR /D %variable IN (set) DO command [command-parameters]

   If set contains wildcards, then specifies to match against directory
   names instead of file names.

FOR /R [[drive:]path] %variable IN (set) DO command [command-parameters]

   Walks the directory tree rooted at [drive:]path, executing the FOR
   statement in each directory of the tree.  If no directory
   specification is specified after /R then the current directory is
   assumed.  If set is just a single period (.) character then it
   will just enumerate the directory tree.

FOR /L %variable IN (start,step,end) DO command [command-parameters]

   The set is a sequence of numbers from start to end, by step amount.
   So (1,1,5) would generate the sequence 1 2 3 4 5 and (5,-1,1) would
   generate the sequence (5 4 3 2 1)

FOR /F ["options"] %variable IN (file-set) DO command [command-parameters] FOR /F ["options"] %variable IN ("string") DO command [command-parameters] FOR /F ["options"] %variable IN ('command') DO command [command-parameters]

   or, if usebackq option present:

FOR /F ["options"] %variable IN (file-set) DO command [command-parameters] FOR /F ["options"] %variable IN ('string') DO command [command-parameters] FOR /F ["options"] %variable IN (`command`) DO command [command-parameters]

   filenameset is one or more file names.  Each file is opened, read
   and processed before going on to the next file in filenameset.
   Processing consists of reading in the file, breaking it up into
   individual lines of text and then parsing each line into zero or
   more tokens.  The body of the for loop is then called with the
   variable value(s) set to the found token string(s).  By default, /F
   passes the first blank separated token from each line of each file.
   Blank lines are skipped.  You can override the default parsing
   behavior by specifying the optional "options" parameter.  This
   is a quoted string which contains one or more keywords to specify
   different parsing options.  The keywords are:

       eol=c           - specifies an end of line comment character
                         (just one)
       skip=n          - specifies the number of lines to skip at the
                         beginning of the file.
       delims=xxx      - specifies a delimiter set.  This replaces the
                         default delimiter set of space and tab.
       tokens=x,y,m-n  - specifies which tokens from each line are to
                         be passed to the for body for each iteration.
                         This will cause additional variable names to
                         be allocated.  The m-n form is a range,
                         specifying the mth through the nth tokens.  If
                         the last character in the tokens= string is an
                         asterisk, then an additional variable is
                         allocated and receives the remaining text on
                         the line after the last token parsed.
       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
                         filenameset.

   Some examples might help:

FOR /F "eol=; tokens=2,3* delims=, " %i in (myfile.txt) do @echo %i %j %k

   would parse each line in myfile.txt, ignoring lines that begin with
   a semicolon, passing the 2nd and 3rd token from each line to the for
   body, with tokens delimited by commas and/or spaces.  Notice the for
   body statements reference %i to get the 2nd token, %j to get the
   3rd token, and %k to get all remaining tokens after the 3rd.  For
   file names that contain spaces, you need to quote the filenames with
   double quotes.  In order to use double quotes in this manner, you also
   need to use the usebackq option, otherwise the double quotes will be
   interpreted as defining a literal string to parse.

   %i is explicitly declared in the for statement and the %j and %k
   are implicitly declared via the tokens= option.  You can specify up
   to 26 tokens via the tokens= line, provided it does not cause an
   attempt to declare a variable higher than the letter 'z' or 'Z'.
   Remember, FOR variables are single-letter, case sensitive, global, 
   and you can't have more than 52 total active at any one time.

   You can also use the FOR /F parsing logic on an immediate string, by
   making the filenameset between the parenthesis a quoted string,
   using single quote characters.  It will be treated as a single line
   of input from a file and parsed.

   Finally, you can use the FOR /F command to parse the output of a
   command.  You do this by making the filenameset 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.

In addition, substitution of FOR variable references has been enhanced. You can now use the following optional syntax:

   %~I         - expands %I removing any surrounding quotes (")
   %~fI        - expands %I to a fully qualified path name
   %~dI        - expands %I to a drive letter only
   %~pI        - expands %I to a path only
   %~nI        - expands %I to a file name only
   %~xI        - expands %I to a file extension only
   %~sI        - expanded path contains short names only
   %~aI        - expands %I to file attributes of file
   %~tI        - expands %I to date/time of file
   %~zI        - expands %I to size of file
   %~$PATH:I   - searches the directories listed in the PATH
                  environment variable and expands %I to the
                  fully qualified name of the first one found.
                  If the environment variable name is not
                  defined or the file is not found by the
                  search, then this modifier expands to the
                  empty string

The modifiers can be combined to get compound results:

   %~dpI       - expands %I to a drive letter and path only
   %~nxI       - expands %I to a file name and extension only
   %~fsI       - expands %I to a full path name with short names only
   %~dp$PATH:I - searches the directories listed in the PATH
                  environment variable for %I and expands to the
                  drive letter and path of the first one found.
   %~ftzaI     - expands %I to a DIR like output line

In the above examples %I and PATH can be replaced by other valid values. The %~ syntax is terminated by a valid FOR variable name. Picking upper case variable names like %I makes it more readable and avoids confusion with the modifiers, which are not case sensitive.