Batch Read Line From File Into Variable

• Batch Read Line From File Into Variable Form
• Batch Read Line From File Into Variable Excel
• Batch Read Line From File Into Variable
• Batch Read Line From File Into Variable Time

Sep 25, 2008 If your set command supports the /p switch, then you can pipe input that way. Set /p VAR1= to set the value of a variable to a line of input entered by the user. Displays the specified promptString before reading the line of input. Aug 16, 2008 The FOR loop will read one line, assign data to variables, then you can process the variables. The FOR loop will then read the next line, and repeat the process. The variables will remain defined with the data from the last line of the config.txt after the batch file ends.

Runs a specified command for each file, within a set of files.

Syntax

Parameters

Remarks

• You can use this command within a batch file or directly from the command prompt.

• The following attributes apply to the for command:

  • This command replaces % variable or %% variable with each text string in the specified set until the specified command processes all of the files.

  • Variable names are case sensitive, global, and no more than 52 can be active at a time.

  • To avoid confusion with the batch parameters, %0 through %9, you can use any character for variable except the numerals 0 through 9. For simple batch files, a single character such as %%f will work.

  • You can use multiple values for variable in complex batch files to distinguish different replaceable variables.

• The set parameter can represent a single group of files or several groups of files. You can use wildcard characters (* and ?) to specify a file set. The following are valid file sets:

• When you use this command, the first value in set replaces % variable or %% variable, and then the specified command processes this value. This continues until all of the files (or groups of files) that correspond to the set value are processed.

• In and do aren't parameters, but you must use them with this command. If you omit either of these keywords, an error message appears.

• If command extensions are enabled (that is the default), the following additional forms of for are supported:

  • Directories only: If set contains wildcard characters (* or ?), the specified command executes for each directory (instead of a set of files in a specified directory) that matches set. The syntax is:

  • Recursive: Walks the directory tree that is rooted at drive:path and executes the for statement in each directory of the tree. If no directory is specified after /r, the current directory is used as the root directory. If set is just a single period (.), it only enumerates the directory tree. The syntax is:

  • Iterating a range of values: Use an iterative variable to set the starting value (start#) and then step through a set range of values until the value exceeds the set ending value (end#). /l will execute the iterative by comparing start# with end#. If start# is less than end# the command will execute. When the iterative variable exceeds end#, the command shell exits the loop. You can also use a negative step# to step through a range in decreasing values. For example, (1,1,5) generates the sequence 1 2 3 4 5 and (5,-1,1) generates the sequence 5 4 3 2 1. The syntax is:

  • Iterating and file parsing: Use file parsing to process command output, strings, and file content. Use iterative variables to define the content or strings that you want to examine, and use the various parsingkeywords options to further modify the parsing. Use the parsingkeywords token option to specify which tokens should be passed as iterative variables. Note that when used without the token option, /f will only examine the first token.

    File parsing consists of reading the output, string, or file content, and then breaking it into individual lines of text and parsing each line into zero or more tokens. The for loop is then called with the iterative variable value set to the token. By default, /f passes the first blank separated token from each line of each file. Blank lines are skipped.

    The syntaxes are:

    The set argument specifies one or more file names. Each file is opened, read, and processed before moving to the next file in set. To override the default parsing behavior, specify parsingkeywords. This is a quoted string that contains one or more keywords to specify different parsing options.

    If you use the usebackq option, use one of the following syntaxes:

    The following table lists the parsing keywords that you can use for parsingkeywords.

    Keyword	Description
    eol=<c>	Specifies an end of line character (just one character).
    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 loop for each iteration. As a result, additional variable names are allocated. m-n specifies a range, from the mth through the nth tokens. If the last character in the tokens= string is an asterisk (*), an additional variable is allocated, and it receives the remaining text on the line after the last token that is parsed.
    usebackq	Specifies to run a back-quoted string as a command, use a single-quoted string as a literal string, or, for long file names that contain spaces, allow file names in <set>, to each be enclosed in double-quotation marks.

  • Variable substitution: The following table lists optional syntax (for any variable I):

    Variable with modifier	Description
    %~I	Expands %I which removes any surrounding quotation marks.
    %~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 name extension only.
    %~sI	Expands path to contain short names only.
    %~aI	Expands %I to the file attributes of file.
    %~tI	Expands %I to the date and time of file.
    %~zI	Expands %I to the size of the file.
    %~$PATH:I	Searches the directories listed in the PATH environment variable and expands %I to the fully qualified name of the first directory found. If the environment variable name is not defined or the file is not found by the search, this modifier expands to the empty string.

    The following table lists modifier combinations that you can use to get compound results.

    Variable with combined modifiers	Description
    %~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 that are 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 an output line that is like dir.

    In the above examples, you can replace %I and PATH with other valid values. A valid for variable name ends the %~ syntax.

    By using uppercase variable names such as %I, you can make your code more readable and avoid confusion with the modifiers, which are not case sensitive.

• Parsing a string: You can use the for /f parsing logic on an immediate string by wrapping <literalstring> in either: double quotes (without usebackq) or in single quotes (with usebackq) --for example, (MyString) or ('MyString'). <literalstring> is treated as a single line of input from a file. When parsing <literalstring> in double-quotes, command symbols (such as, & | > < ^) are treated as ordinary characters.

• Parsing output: You can use the for /f command to parse the output of a command by placing a back-quoted <command> between the parentheses. It is treated as a command line, which is passed to a child Cmd.exe. The output is captured into memory and parsed as if it is a file.

Examples

To use for in a batch file, use the following syntax:

To display the contents of all the files in the current directory that have the extension .doc or .txt by using the replaceable variable %f, type:

In the preceding example, each file that has the .doc or .txt extension in the current directory is substituted for the %f variable until the contents of every file are displayed. To use this command in a batch file, replace every occurrence of %f with %%f. Otherwise, the variable is ignored and an error message is displayed.

To parse a file, ignoring commented lines, type:

This command parses each line in myfile.txt. It ignores lines that begin with a semicolon and passes the second and third token from each line to the for body (tokens are delimited by commas or spaces). The body of the for statement references %i to get the second token, %j to get the third token, and %k to get all of the remaining tokens. If the file names that you supply contain spaces, use quotation marks around the text (for example, File Name). To use quotation marks, you must use usebackq. Otherwise, the quotation marks are interpreted as defining a literal string to parse.

%i is explicitly declared in the for statement. %j and %k are implicitly declared by using tokens=. You can use tokens= to specify up to 26 tokens, provided that it does not cause an attempt to declare a variable higher than the letter z or Z.

To parse the output of a command by placing set between the parentheses, type:

Additional References

Batch file to read a text file and perform actions

I do a lot of repetitive things on Windows pcs and servers. Often, I’ll need to do the same thing on 10 or more machines, like delete old log files or database backups older than a certain age. In the past, I created a complicated batch file to do a bunch of tasks, but it was annoying to customize it for each location. I tried adding a “profile” for each machine that had path info for common programs and file locations, but that quickly got out of hand too.

I could have installed any one of a number of scripting “languages” to make it easier, but that would have just added another layer of complexity. I just needed a simple way to read a text file and pipe each line to a command. Then I re-discovered FOR…

FOR runs a command for each file in a set of files. You can specify the command and file set on the commandline itself, or read them from other files.

Batch Read Line From File Into Variable Form

Here’s a couple of references to check out:
Microsoft
ss64

Read lines in a file & echo them

Updated 06/30/2012 with the most basic usage.

This does nothing except read a file line by line and echo it. “%%f” is the parameter (variable name) for the line being read and “echo %%f” is the action that DO performs. Use this as a starting point to create your own batch file.

echo off
FOR /F 'delims=|' %%f in (your_file.txt) DO echo %%f


read_do.bat

Here’s my simple batch file that reads a text file, line by line, and passes each line to another batch file to perform an action. The second variable, “%%g”, is there because DelOld expects 2 parameters and FOR interprets a space in a line as a delimiter. There is a way to avoid the space as a delimiter, but this was easier and the other programs don’t seem to care. You could also pass more variables by using “%%h”, etc.


CLS
@echo off
::#########################################
ECHO #########################################
ECHO Read file and perform action
ECHO Usage: read_do.bat (filename.txt) (action.bat)
ECHO.
ECHO Text files:
dir /B /w *.txt
ECHO.
ECHO Action (.bat) files:
dir /w /B *.bat
ECHO.
ECHO #########################################
ECHO.
REM sanity check
ECHO Text file contents:
FOR /F 'delims=|' %%f in (%1) DO echo %%f %%g
PAUSE
FOR /F 'delims=|' %%f in (%1) DO CALL %2 %%f %%g


The examples below should be self-explanatory.

Example 1 – Delete a variety of old, mostly .log, files from known locations

I use the VB version of DelOld (Michna.com) to get rid of old log files, and in some cases backups, after X number of days. DelOld expects a complete path to the file or directory to delete and a value in days for the minimum age of the files.

This is a list of the commandlines I want to send to DelOld. I’ve had mixed results with quoted long paths, but 8.3 style seems to work every time.

delold.txt:

c:docume~1%USERNAME%LocalS~1Applic~12Brigh~1SyncBackLogs*.html 10
c:progra~1logmeinlmi*.log 10
c:backup*rsync*.log 10


delold.bat:

REM path to delold.exe plus filename to delete (%1) & how many days old (%2)
c:delold %1 %2


Example 2 – make several file types contiguous

Batch Read Line From File Into Variable Excel

Use Microsoft (Sysinternals) Contig (TechNet) to make a list of files or file types contiguous.

contigs.txt:

c:*.log
e:*.log
c:*.dat
e:*.dat


contig.bat:

REM path to contig.exe plus file(s) to contig (%1)
c:sysinternalscontig -s %1


Example 3 – copy/update a list of websites for offline browsing or backup

Use wget for Windows (SourceForge) to download a list of sites, each in its own directory and fix the links for local browsing. There’s a bewildering array of options for wget that might suit your needs better than this.

sitelist.txt:

http://computingconsultants.com
http://ohio-funeral-homes.com
http://spywarekillers.info
http://betta-fish-care.info


Batch Read Line From File Into Variable

wget_site.bat:

Batch Read Line From File Into Variable Time


SET dest=pathtosavelocation
C:wgetwget.exe -N -e robots=off -r %1 -P%dest%