How does the Windows RENAME (REN) command interpret wildcards?

The built in HELP facility is of no help - it doesn't address wildcards at all.

The Microsoft technet XP online help isn't much better. Here is all it has to say regarding wildcards:

"You can use wildcards (* and ?) in either file name parameter. If you use wildcards in filename2, the characters represented by the wildcards will be identical to the corresponding characters in filename1."

Not much help - there are many ways that statement can be interpretted.

I've managed to successfully use wildcards in the filename2 parameter on some occasions, but it has always been trial and error. I haven't been able to anticipate what works and what doesn't. Frequently I've had to resort to writing a small batch script with a FOR loop that parses each name so that I can build each new name as needed. Not very convenient.

If I knew the rules for how wildcards are processed then I figure I could use the RENAME command more effectively without having to resort to batch as often. Of course knowing the rules would also benefit batch development.

(Yes - this is a case where I am posting a paired question and answer. I got tired of not knowing the rules and decided to experiment on my own. I figure many others may be interested in what I discovered)

  • There's heaps of good examples of how to rename with wildcards here: lagmonster.org/docs/DOS7/z-ren1.html Commented Aug 20, 2013 at 7:38
  • 7
    @MatthewLock - Interesting link, but those rules and examples are for MSDOS 7, not Windows. There are significant differences. For example, MSDOS does not allow appending additional chars after *, Windows does. That has huge consequences. I wish I had known about that site though; it might have made my investigation easier. The MSDOS7 rules are significantly different then the old DOS rules before long file names, and they are a step in the direction of how Windows handles it. I had found the pre long file name DOS rules, and they were worthless for my investigation.
    – dbenham
    Commented Aug 20, 2013 at 11:43
  • I did not know that ;) Commented Aug 20, 2013 at 13:14

7 Answers 7


These rules were discovered after extensive testing on a Vista machine. No tests were done with unicode in file names.

RENAME requires 2 parameters - a sourceMask, followed by a targetMask. Both the sourceMask and targetMask can contain * and/or ? wildcards. The behavior of the wildcards changes slightly between source and target masks.

Note - REN can be used to rename a folder, but wildcards are not allowed in either the sourceMask or targetMask when renaming a folder. If the sourceMask matches at least one file, then the file(s) will be renamed and folders will be ignored. If the sourceMask matches only folders and not files, then a syntax error is generated if wildcards appear in source or target. If the sourceMask does not match anything, then a "file not found" error results.

Also, when renaming files, wildcards are only allowed in the file name portion of the sourceMask. Wildcards are not allowed in the path leading up to the file name.


The sourceMask works as a filter to determine which files are renamed. The wildcards work here the same as with any other command that filters file names.

  • ? - Matches any 0 or 1 character except . This wildcard is greedy - it always consumes the next character if it is not a . However it will match nothing without failure if at name end or if the next character is a .

  • * - Matches any 0 or more characters including . (with one exception below). This wildcard is not greedy. It will match as little or as much as is needed to enable subsequent characters to match.

All non-wildcard characters must match themselves, with a few special case exceptions.

  • . - Matches itself or it can match the end of name (nothing) if no more characters remain. (Note - a valid Windows name cannot end with .)

  • {space} - Matches itself or it can match the end of name (nothing) if no more characters remain. (Note - a valid Windows name cannot end with {space})

  • *. at the end - Matches any 0 or more characters except . The terminating . can actually be any combination of . and {space} as long as the very last character in the mask is . This is the one and only exception where * does not simply match any set of characters.

The above rules are not that complex. But there is one more very important rule that makes the situation confusing: The sourceMask is compared against both the long name and the short 8.3 name (if it exists). This last rule can make interpretation of the results very tricky, because it is not always obvious when the mask is matching via the short name.

It is possible to use RegEdit to disable the generation of short 8.3 names on NTFS volumes, at which point interpretation of file mask results is much more straight forward. Any short names that were generated before disabling short names will remain.


Note - I haven't done any rigorous testing, but it appears these same rules also work for the target name of the COPY commmand

The targetMask specifies the new name. It is always applied to the full long name; The targetMask is never applied to the short 8.3 name, even if the sourceMask matched the short 8.3 name.

The presence or absence of wildcards in the sourceMask has no impact on how wildcards are processed in the targetMask.

In the following discussion - c represents any character that is not *, ?, or .

The targetMask is processed against the source name strictly from left to right with no back-tracking.

  • c - Advances the position within the source name only if the source character is not ., and always appends c to the target name. (Replaces the character that was in source with c, but never replaces .)

  • ? - Matches the next character from the source long name and appends it to the target name as long as the source character is not . If the next character is . or if at the end of the source name then no character is added to the result and the current position within the source name is unchanged.

  • * at end of targetMask - Appends all remaining characters from source to the target. If already at the end of source, then does nothing.

  • *c - Matches all source characters from current position through the last occurance of c (case sensitive greedy match) and appends the matched set of characters to the target name. If c is not found, then all remaining characters from source are appended, followed by c This is the only situation I am aware of where Windows file pattern matching is case sensitive.

  • *. - Matches all source characters from current position through the last occurance of . (greedy match) and appends the matched set of characters to the target name. If . is not found, then all remaining characters from source are appended, followed by .

  • *? - Appends all remaining characters from source to the target. If already at end of source then does nothing.

  • . without * in front - Advances the position in source through the first occurance of . without copying any characters, and appends . to the target name. If . is not found in the source, then advances to the end of source and appends . to the target name.

After the targetMask has been exhausted, any trailing . and {space} are trimmed off the end of the resulting target name because Windows file names cannot end with . or {space}

Some practical examples

Substitute a character in the 1st and 3rd positions prior to any extension (adds a 2nd or 3rd character if it doesn't exist yet)

ren  *  A?Z*
  1        -> AZ
  12       -> A2Z
  1.txt    -> AZ.txt
  12.txt   -> A2Z.txt
  123      -> A2Z
  123.txt  -> A2Z.txt
  1234     -> A2Z4
  1234.txt -> A2Z4.txt

Change the (final) extension of every file

ren  *  *.txt
  a     -> a.txt
  b.dat -> b.txt
  c.x.y -> c.x.txt

Append an extension to every file

ren  *  *?.bak
  a     -> a.bak
  b.dat -> b.dat.bak
  c.x.y -> c.x.y.bak

Remove any extra extension after the initial extension. Note that adequate ? must be used to preserve the full existing name and initial extension.

ren  *  ?????.?????
  a     -> a
  a.b   -> a.b
  a.b.c -> a.b
  part1.part2.part3    -> part1.part2
  123456.123456.123456 -> 12345.12345   (note truncated name and extension because not enough `?` were used)

Same as above, but filter out files with initial name and/or extension longer than 5 chars so that they are not truncated. (Obviously could add an additional ? on either end of targetMask to preserve names and extensions up to 6 chars long)

ren  ?????.?????.*  ?????.?????
  a      ->  a
  a.b    ->  a.b
  a.b.c  ->  a.b
  part1.part2.part3  ->  part1.part2
  123456.123456.123456  (Not renamed because doesn't match sourceMask)

Change characters after last _ in name and attempt to preserve extension. (Doesn't work properly if _ appears in extension)

ren  *_*  *_NEW.*
  abcd_12345.txt  ->  abcd_NEW.txt
  abc_newt_1.dat  ->  abc_newt_NEW.dat
  abcdef.jpg          (Not renamed because doesn't match sourceMask)
  abcd_123.a_b    ->  abcd_123.a_NEW  (not desired, but no simple RENAME form will work in this case)

Any name can be broken up into components that are delimited by . Characters may only be appended to or deleted from the end of each component. Characters cannot be deleted from or added to the beginning or middle of a component while preserving the remainder with wildcards. Substitutions are allowed anywhere.

ren  ??????.??????.??????  ?x.????999.*rForTheCourse
  part1.part2            ->  px.part999.rForTheCourse
  part1.part2.part3      ->  px.part999.parForTheCourse
  part1.part2.part3.part4   (Not renamed because doesn't match sourceMask)
  a.b.c                  ->  ax.b999.crForTheCourse
  a.b.CarPart3BEER       ->  ax.b999.CarParForTheCourse

If short names are enabled, then a sourceMask with at least 8 ? for the name and at least 3 ? for the extension will match all files because it will always match the short 8.3 name.

ren ????????.???  ?x.????999.*rForTheCourse
  part1.part2.part3.part4  ->  px.part999.part3.parForTheCourse

Useful quirk/bug? for deleting name prefixes

This SuperUser post describes how a set of forward slashes (/) can be used to delete leading characters (except .) from a file name. One slash is required for each character to be deleted. I've confirmed the behavior on a Windows 10 machine.

ren "abc-*.txt" "////*.txt"
  abc-123.txt        --> 123.txt
  abc-HelloWorld.txt --> HelloWorld.txt

Unfortunately leading / cannot remove . in a name. So the technique cannot be used to remove a prefix that contains .. For example:

ren "abc.xyz.*.txt" "////////*.txt"
  abc.xyz.123.txt        --> .xyz.123.txt
  abc.xyz.HelloWorld.txt --> .xyz.HelloWorld.txt

This technique only works if both the source and target masks are enclosed in double quotes. All of the following forms without the requisite quotes fail with this error: The syntax of the command is incorrect

REM - All of these forms fail with a syntax error.
ren abc-*.txt "////*.txt"
ren "abc-*.txt" ////*.txt
ren abc-*.txt ////*.txt

The / cannot be used to remove any characters in the middle or end of a file name. It can only remove leading (prefix) characters. Also note this technique does not work with folder names.

Technically the / is not functioning as a wildcard. Rather it is doing a simple character substitution following the c target mask rule. But then after the substitution, the REN command recognizes that / is not valid in a file name, and strips the leading / slashes from the name. REN gives a syntax error if it detects / in the middle of a target name.

Possible RENAME bug - a single command may rename the same file twice!

Starting in an empty test folder:

C:\test>copy nul 123456789.123
        1 file(s) copied.

C:\test>dir /x
 Volume in drive C is OS
 Volume Serial Number is EE2C-5A11

 Directory of C:\test

09/15/2012  07:42 PM    <DIR>                       .
09/15/2012  07:42 PM    <DIR>                       ..
09/15/2012  07:42 PM                 0 123456~1.123 123456789.123
               1 File(s)              0 bytes
               2 Dir(s)  327,237,562,368 bytes free

C:\test>ren *1* 2*3.?x

C:\test>dir /x
 Volume in drive C is OS
 Volume Serial Number is EE2C-5A11

 Directory of C:\test

09/15/2012  07:42 PM    <DIR>                       .
09/15/2012  07:42 PM    <DIR>                       ..
09/15/2012  07:42 PM                 0 223456~1.XX  223456789.123.xx
               1 File(s)              0 bytes
               2 Dir(s)  327,237,562,368 bytes free

REM Expected result = 223456789.123.x

I believe the sourceMask *1* first matches the long file name, and the file is renamed to the expected result of 223456789.123.x. RENAME then continues to look for more files to process and finds the newly named file via the new short name of 223456~1.X. The file is then renamed again giving the final result of 223456789.123.xx.

If I disable 8.3 name generation then the RENAME gives the expected result.

I haven't fully worked out all of the trigger conditions that must exist to induce this odd behavior. I was concerned that it might be possible to create a never ending recursive RENAME, but I was never able to induce one.

I believe all of the following must be true to induce the bug. Every bugged case I saw had the following conditions, but not all cases that met the following conditions were bugged.

  • Short 8.3 names must be enabled
  • The sourceMask must match the original long name.
  • The initial rename must generate a short name that also matches the sourceMask
  • The initial renamed short name must sort later than the original short name (if it existed?)
  • 10
    What a thorough answer.. +1. Commented Oct 5, 2012 at 19:48
  • Tremendously elaborate!
    – Andriy M
    Commented Mar 6, 2013 at 5:39
  • 16
    Based on this, Microsoft should just add "For usage, see superuser.com/a/475875 " in REN /?.
    – efotinis
    Commented Jun 14, 2013 at 21:27
  • 7
    @CAD - This answer is 100% original content that Simon included on his site upon my request. Look at the bottom of that SS64 page and you will see that Simon gives me credit for the work.
    – dbenham
    Commented Mar 14, 2017 at 3:46
  • 3
    @JacksOnF1re - New information/technique added to my answer. You can actually delete your Copy of prefix using an obscure forward slash technique: ren "Copy of *.txt" "////////*"
    – dbenham
    Commented Jun 3, 2017 at 19:33

Similar to exebook, here's a C# implementation to get the target filename from a sourcefile.

I found 1 small error in dbenham's examples:

 ren  *_*  *_NEW.*
   abc_newt_1.dat  ->  abc_newt_NEW.txt (should be: abd_newt_NEW.dat)

Here's the code:

    /// <summary>
    /// Returns a filename based on the sourcefile and the targetMask, as used in the second argument in rename/copy operations.
    /// targetMask may contain wildcards (* and ?).
    /// This follows the rules of: http://superuser.com/questions/475874/how-does-the-windows-rename-command-interpret-wildcards
    /// </summary>
    /// <param name="sourcefile">filename to change to target without wildcards</param>
    /// <param name="targetMask">mask with wildcards</param>
    /// <returns>a valid target filename given sourcefile and targetMask</returns>
    public static string GetTargetFileName(string sourcefile, string targetMask)
        if (string.IsNullOrEmpty(sourcefile))
            throw new ArgumentNullException("sourcefile");

        if (string.IsNullOrEmpty(targetMask))
            throw new ArgumentNullException("targetMask");

        if (sourcefile.Contains('*') || sourcefile.Contains('?'))
            throw new ArgumentException("sourcefile cannot contain wildcards");

        // no wildcards: return complete mask as file
        if (!targetMask.Contains('*') && !targetMask.Contains('?'))
            return targetMask;

        var maskReader = new StringReader(targetMask);
        var sourceReader = new StringReader(sourcefile);
        var targetBuilder = new StringBuilder();

        while (maskReader.Peek() != -1)

            int current = maskReader.Read();
            int sourcePeek = sourceReader.Peek();
            switch (current)
                case '*':
                    int next = maskReader.Read();
                    switch (next)
                        case -1:
                        case '?':
                            // Append all remaining characters from sourcefile
                            // Read source until the last occurrance of 'next'.
                            // We cannot seek in the StringReader, so we will create a new StringReader if needed
                            string sourceTail = sourceReader.ReadToEnd();
                            int lastIndexOf = sourceTail.LastIndexOf((char) next);
                            // If not found, append everything and the 'next' char
                            if (lastIndexOf == -1)
                                targetBuilder.Append((char) next);

                                string toAppend = sourceTail.Substring(0, lastIndexOf + 1);
                                string rest = sourceTail.Substring(lastIndexOf + 1);
                                // go on with the rest...
                                sourceReader = new StringReader(rest);

                case '?':
                    if (sourcePeek != -1 && sourcePeek != '.')
                case '.':
                    // eat all characters until the dot is found
                    while (sourcePeek != -1 && sourcePeek != '.')
                        sourcePeek = sourceReader.Peek();

                    // need to eat the . when we peeked it
                    if (sourcePeek == '.')

                    if (sourcePeek != '.') sourceReader.Read(); // also consume the source's char if not .


        return targetBuilder.ToString().TrimEnd('.', ' ');

And here's an NUnit test method to test the examples:

    public void TestGetTargetFileName()
        string targetMask = "?????.?????";
        Assert.AreEqual("a", FileUtil.GetTargetFileName("a", targetMask));
        Assert.AreEqual("a.b", FileUtil.GetTargetFileName("a.b", targetMask));
        Assert.AreEqual("a.b", FileUtil.GetTargetFileName("a.b.c", targetMask));
        Assert.AreEqual("part1.part2", FileUtil.GetTargetFileName("part1.part2.part3", targetMask));
        Assert.AreEqual("12345.12345", FileUtil.GetTargetFileName("123456.123456.123456", targetMask));

        targetMask = "A?Z*";
        Assert.AreEqual("AZ", FileUtil.GetTargetFileName("1", targetMask));
        Assert.AreEqual("A2Z", FileUtil.GetTargetFileName("12", targetMask));
        Assert.AreEqual("AZ.txt", FileUtil.GetTargetFileName("1.txt", targetMask));
        Assert.AreEqual("A2Z.txt", FileUtil.GetTargetFileName("12.txt", targetMask));
        Assert.AreEqual("A2Z", FileUtil.GetTargetFileName("123", targetMask));
        Assert.AreEqual("A2Z.txt", FileUtil.GetTargetFileName("123.txt", targetMask));
        Assert.AreEqual("A2Z4", FileUtil.GetTargetFileName("1234", targetMask));
        Assert.AreEqual("A2Z4.txt", FileUtil.GetTargetFileName("1234.txt", targetMask));

        targetMask = "*.txt";
        Assert.AreEqual("a.txt", FileUtil.GetTargetFileName("a", targetMask));
        Assert.AreEqual("b.txt", FileUtil.GetTargetFileName("b.dat", targetMask));
        Assert.AreEqual("c.x.txt", FileUtil.GetTargetFileName("c.x.y", targetMask));

        targetMask = "*?.bak";
        Assert.AreEqual("a.bak", FileUtil.GetTargetFileName("a", targetMask));
        Assert.AreEqual("b.dat.bak", FileUtil.GetTargetFileName("b.dat", targetMask));
        Assert.AreEqual("c.x.y.bak", FileUtil.GetTargetFileName("c.x.y", targetMask));

        targetMask = "*_NEW.*";
        Assert.AreEqual("abcd_NEW.txt", FileUtil.GetTargetFileName("abcd_12345.txt", targetMask));
        Assert.AreEqual("abc_newt_NEW.dat", FileUtil.GetTargetFileName("abc_newt_1.dat", targetMask));
        Assert.AreEqual("abcd_123.a_NEW", FileUtil.GetTargetFileName("abcd_123.a_b", targetMask));

        targetMask = "?x.????999.*rForTheCourse";

        Assert.AreEqual("px.part999.rForTheCourse", FileUtil.GetTargetFileName("part1.part2", targetMask));
        Assert.AreEqual("px.part999.parForTheCourse", FileUtil.GetTargetFileName("part1.part2.part3", targetMask));
        Assert.AreEqual("ax.b999.crForTheCourse", FileUtil.GetTargetFileName("a.b.c", targetMask));
        Assert.AreEqual("ax.b999.CarParForTheCourse", FileUtil.GetTargetFileName("a.b.CarPart3BEER", targetMask));

  • Thanks for the head's up about the mistake in my example. I've edited my answer to fix it.
    – dbenham
    Commented Dec 16, 2014 at 12:16

I have managed to write this code in BASIC to mask wildcard filenames:

REM inputs a filename and matches wildcards returning masked output filename.
FUNCTION maskNewName$ (path$, mask$)
IF INSTR(path$, "?") OR INSTR(path$, "*") THEN EXIT FUNCTION
x = 0
R$ = ""
FOR m = 0 TO LEN(mask$) - 1
    ch$ = MID$(mask$, m + 1, 1)
    q$ = MID$(path$, x + 1, 1)
    z$ = MID$(mask$, m + 2, 1)
    IF ch$ <> "." AND ch$ <> "*" AND ch$ <> "?" THEN
        IF LEN(q$) AND q$ <> "." THEN x = x + 1
        R$ = R$ + ch$
        IF ch$ = "?" THEN
            IF LEN(q$) AND q$ <> "." THEN R$ = R$ + q$: x = x + 1
            IF ch$ = "*" AND m = LEN(mask$) - 1 THEN
                WHILE x < LEN(path$)
                    R$ = R$ + MID$(path$, x + 1, 1)
                    x = x + 1
                IF ch$ = "*" THEN
                    IF z$ = "." THEN
                        FOR i = LEN(path$) - 1 TO 0 STEP -1
                            IF MID$(path$, i + 1, 1) = "." THEN EXIT FOR
                        IF i < 0 THEN
                            R$ = R$ + MID$(path$, x + 1) + "."
                            i = LEN(path$)
                            R$ = R$ + MID$(path$, x + 1, i - x + 1)
                        END IF
                        x = i + 1
                        m = m + 1
                        IF z$ = "?" THEN
                            R$ = R$ + MID$(path$, x + 1, LEN(path$))
                            m = m + 1
                            x = LEN(path$)
                            FOR i = LEN(path$) - 1 TO 0 STEP -1
                                'IF MID$(path$, i + 1, 1) = z$ THEN EXIT FOR
                                IF UCASE$(MID$(path$, i + 1, 1)) = UCASE$(z$) THEN EXIT FOR
                            IF i < 0 THEN
                                R$ = R$ + MID$(path$, x + 1, LEN(path$)) + z$
                                x = LEN(path$)
                                m = m + 1
                                R$ = R$ + MID$(path$, x + 1, i - x)
                                x = i + 1
                            END IF
                        END IF
                    END IF
                    IF ch$ = "." THEN
                        DO WHILE x < LEN(path$)
                            IF MID$(path$, x + 1, 1) = "." THEN
                                x = x + 1
                                EXIT DO
                            END IF
                            x = x + 1
                        R$ = R$ + "."
                    END IF
                END IF
            END IF
        END IF
    END IF
DO WHILE RIGHT$(R$, 1) = "."
    R$ = LEFT$(R$, LEN(R$) - 1)
R$ = RTRIM$(R$)
maskNewName$ = R$
  • 5
    Can you clarify how this answers what was asked in the question?
    – fixer1234
    Commented Oct 13, 2016 at 3:58
  • It replicates the function REN uses for wildcard matching such as processing REN *.TMP *.DOC depending on how the function is called before renaming the filenames.
    – eoredson
    Commented Oct 13, 2016 at 21:08

Maybe someone can find this useful. This JavaScript code is based on the answer by dbenham above.

I did not test sourceMask very much, but targetMask does match all examples given by dbenham.

function maskMatch(path, mask) {
    mask = mask.replace(/\./g, '\\.')
    mask = mask.replace(/\?/g, '.')
    mask = mask.replace(/\*/g, '.+?')
    var r = new RegExp('^'+mask+'$', '')
    return path.match(r)

function maskNewName(path, mask) {
    if (path == '') return
    var x = 0, R = ''
    for (var m = 0; m < mask.length; m++) {
        var ch = mask[m], q = path[x], z = mask[m + 1]
        if (ch != '.' && ch != '*' && ch != '?') {
            if (q && q != '.') x++
            R += ch
        } else if (ch == '?') {
            if (q && q != '.') R += q, x++
        } else if (ch == '*' && m == mask.length - 1) {
            while (x < path.length) R += path[x++]
        } else if (ch == '*') {
            if (z == '.') {
                for (var i = path.length - 1; i >= 0; i--) if (path[i] == '.') break
                if (i < 0) {
                    R += path.substr(x, path.length) + '.'
                    i = path.length
                } else R += path.substr(x, i - x + 1)
                x = i + 1, m++
            } else if (z == '?') {
                R += path.substr(x, path.length), m++, x = path.length
            } else {
                for (var i = path.length - 1; i >= 0; i--) if (path[i] == z) break
                if (i < 0) R += path.substr(x, path.length) + z, x = path.length, m++
                else R += path.substr(x, i - x), x = i + 1
        } else if (ch == '.') {
            while (x < path.length) if (path[x++] == '.') break
            R += '.'
    while (R[R.length - 1] == '.') R = R.substr(0, R.length - 1)

I have to make an annotation:

"ren" is NOT equal to "rename", at least not in 2021 on Windows 10 / Server 2016.

The rename command works ... but ren has a bug

the star is dropped in target name in case it is combined with environment variables like %random% or %date%

%random% is taken only once when using the ren command... ren .txt %random%.txt will effectively be "greedy", the star is eaten. Ren will produce things like 12521.txt with the first file and then stop saying duplicate file exists...

Example: I have



with ren

ren "*.txt" "%random%*.txt"

A duplicate file name exists, or the file cannot be found.

Dir shows



with rename (%random% is now different):

rename "*.txt" "%random%*.txt"




The rename command having exactly the same parameters does work.

When my wife tells me that I need to be punished then I will file a support request with Microsoft. I am eligible to that, but the last time I did that it was a very unpleasant experience doing this on the "professional" level coming from MSDN. I am also from software industry but not Microsoft but I can predict that this will get the lowest priority and lowest severity so I just don't do this.

  • 1
    As per all docs I have ever seen, as well as experience, REN is an absolute synonym of RENAME - they share the exact same code. I just ran a quick test of rename *.txt %random%.txt on Win 10, and it gave the expected behavior you described with REN - one file was renamed as some number, followed by .txt. The other files generated the error message A duplicate file name exists, or the file cannot be found. This is exactly what I expected. I am 99% sure you are misinterpreting and/or misrepresenting what you are seeing.
    – dbenham
    Commented May 10, 2021 at 10:46

I have run into a case that it is either an overlooked or undocumented special character, or just a bug. This is the underscore '_' character when used mixed with wildcards. For example:

ren A_B.TXT AB.TXT (this works as expected)

ren A_*.TXT A*.TXT (does nothing ??)

ren A_?.TXT A?.TXT (result A_.TXT)

given the existing files:




ren A_B_*.TXT A_*.TXT (does nothing)

ren A_B_?.TXT A_?.TXT (gives one instance of A_B.TXT and two duplicate name errors)

This makes difficult to remove or replace constant parts of similar file names containing the underscore character.


Googling around I found the solution using powershell (Windows). The following command did the trick for me:

get-childitem *.IIQ | foreach { rename-item $_ $_.Name.Replace("XXX_rec_14_cap", "Cap") }

  • The results you are seeing are exactly predicted by my answer. So undocumented by Microsoft - Yes. Overlooked by prior answers - No. The underscore has no special meaning to REN - it is an ordinary character,
    – dbenham
    Commented Jul 23, 2021 at 22:04

The Windows RENAME command, also known as the REN command, allows you to rename files and directories from the command prompt. When using wildcards with the RENAME command, it interprets them in the following ways:

Asterisk (*) Wildcard: The asterisk wildcard represents any sequence of characters, including no characters or multiple characters. For example:

REN *.txt .bak renames all files with the .txt extension to have the .bak extension. REN file.txt newfile.txt renames all files starting with "file" and ending with .txt to "newfile.txt". Question Mark (?) Wildcard: The question mark wildcard represents any single character. For example:

REN file?.txt newfile.txt renames files with the name "file" followed by any single character and ending with .txt to "newfile.txt". Directory Wildcard: The RENAME command does not support wildcards for directories. It can only rename individual files. To rename directories, you need to use other commands like MOVE or ROBOCOPY with appropriate options.

It's important to exercise caution when using wildcards with the RENAME command to ensure that you are targeting the correct files

  • Avoid posting answers to old questions that already got well received answers unless you have something substantial and new to add.
    – Toto
    Commented Jun 22, 2023 at 8:19
  • Your answer offers no new information, and the information you do provide is wrong or incomplete. For example, ? does not represent any single character, but rather any 0 or 1 character. Also ? never matches .
    – dbenham
    Commented Jul 14, 2023 at 19:23

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