nk23x
9/4/2015 - 2:59 PM

Windows Batch File: FOR and expansions

Windows Batch File: FOR and expansions

From for/?
 
 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]
 
 file-set is one or more file names. Each file is opened, read
 and processed before going on to the next file in file-set.
 
 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
 file-set.
 
 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 file-set 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 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.
 
 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.
 
 http://www.eightforums.com/general-support/60814-need-batch-file-help-post471799.html#post471799