Content

MS DOS Command: FOR

Reference from Microsoft WinXP cmd help

Description

For each file in a set of files DO/run a specified command when the specified parameter is met.

Syntax

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

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.

Remarks

Specified %%variable instead of %variable when using in a batch program.

Variable names are case sensitive.

Command Extensions

Syntax

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

Remarks

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

Syntax

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

Remarks

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.

Syntax

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

Remarks

The set (start,step,end) is a sequence of numbers from start to end by step. Negative step is allowed. Imply set (1,2,5) equals to set (1,3,5) and set (5,2,1) equals to set (5,3,1).

Syntax

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]

Remarks

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. The default parsing behavior can be override 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.

Example:

FOR /F "eol=; tokens2,3* delims=, " %i IN (myfile.txt) DO @echo %i %j %k

Do:    Command 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 token 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 cannot 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.

Example:

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

Do:    Command would enumerate the environment variable names in the current environment.

In addition, substitution of FOR variable references has been enhanced with 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 f 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 lik e 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.