Help for the cmd.exe "for" command

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 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. Warning: you can't use a pipe (|) or a call in such a command! Also, there is another difference in the backquote and singel quote string invocations of this command: backquoted strings are executed in a CHILD cmd.exe whereas the single quoted strings are executed in this running session. The difference is the environment variables! 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 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. 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.