Bulk rename files or directories in Linux

Applicable To: Unix, Linux, All 32/64 bit Unix like OS.

We will use a bunch of files to demonstrate the use of the Unix bulk renaming tool: rnm. We will apply replacement, modification, case-conversion, indexing etc.. on the file names and rename them accordingly. We will also apply selective renaming (search functionality) to the files/directories.

These are the files that we are going use for our examples:

abc.png
def.png
ghi.png
jkl.png
abc.jpg
def.jpg
ghi.jpg
jkl.jpg

These files will get changed in each operation and in some cases we may undo some rename operation with rnm -u command for specific purposes.

1. Lowercase-Uppercase conversion:

A common task which appears in mind for file renaming is to convert uppercase file names to lower case and vice-versa. With rnm, we can apply case-conversion to the whole file name as well as part of the file name. To change the case for a part of the file name, we will select that part with regex and replace it with it's upper or lower case (\c for lower case, \C for uppercase).

1.1 Changing the full filename to uppercase or lower case:

We will pass all the filenames in current directory (./*) as arguments.

rnm -rs '/.*/\C/' ./*

This is how the files will look like after the above command:

ABC.JPG
ABC.PNG
DEF.JPG
DEF.PNG
GHI.JPG
GHI.PNG
JKL.JPG
JKL.PNG

Explanation:

-rs takes a replace string. Replace string is comprised of three parts (separated by /): selection part, replace part and modifier. In the above command, .* is the selection part, it selects all i.e the full name of the file, and \C is the replace part. Modifier part is empty here. In the replace part \C (capital C) points to the upper case version of the actual selected part of the filename (for lowercase it's \c with a small c). So basically, the selected part (whole filename) is being replaced with its uppercase version.

Now let's do a lowercase conversion:

rnm -y -rs '/.*/\c/' ./*

Now it will look like this:

abc.jpg
abc.png
def.jpg
def.png
ghi.jpg
ghi.png
jkl.jpg
jkl.png

The -y flag confirms all to yes. If it is not given, rnm asks for confirmation before actual renaming.

1.2 Applying uppercase-lowercase conversion on filenames partially:

Now, lets change the case of filenames without the extensions, i.e .jpg, .png should be intact. To do that we will have to select the part before the last . and replace it with its case-converted version.

This command will do that:

rnm -rs '/.*\./\C/' ./*

Now the files in our directory:

ABC.jpg
ABC.png
DEF.jpg
DEF.png
GHI.jpg
GHI.png
JKL.jpg
JKL.png

.*\. selects the string from beginning to the occurrence of . and replaces with its uppercase-version. You could do the same with the extension too. To select the extension, you would have to use the regex \.*.

rnm has built-in support for extension management. For filename extensions, you generally have to care for several things, like for a file named .config, you can't say that the config part is the extension. Hidden files in Linux starts with a dot at the beginning and those don't generally have extensions. So it's better to use the built-in functionality of rnm to handle filename extensions. Here's an example of doing the same thing as above with built-in filename extension support:

rnm -rs '//n//\C/' ./*

/n/ is a Name String Rule and equals to the filename without extension.

To do the same on the extensions:

rnm -rs '//e/$/\C/' ./*

/e/ is another Name String Rule which equals to the extension of the file. For files like .config this remains empty. The $ (regex) makes sure the extension is selected at the end, not anywhere else in the filename.

1.3 Applying multiple uppercase-lowercase conversions:

This time we are going to change the case of several letters in the file name, literally 'a', 'j', 'n'. Obviously we can do it in three steps with three rnm commands, but we are going to do it with a single command. The current sate of the filenames in our directory are all small-letters.

Files:

abc.jpg  abc.png  def.jpg  def.png  ghi.jpg  ghi.png  jkl.jpg  jkl.png

Let's run the command:

rnm -rs '/a/\C/;/g/\C/g;/n/\C/' ./*

The files will look like:

Abc.jpG  Abc.pNG  def.jpG  def.pNG  Ghi.jpG  Ghi.pNG  jkl.jpG  jkl.pNG

As you can see, the -rs option can take multiple Replace Strings terminated with a semicolon (;). Notice the replace string: /g/\C/g, here we have used a modifier g which means global i.e the replacement will be applied to every occurrences (Not only the first occurrence) of g found on the filename.

2 Replace, modify, delete, swap part of a filename:

As we have already seen that -rs option takes a Replace String and performs replacement on filenames, we can use this to replace, modify or delete part of a filename or the change the whole filename altogether.

The current state of the files in our directory:

abc.jpg
abc.png
def.jpg
def.png
ghi.jpg
ghi.png
jkl.jpg
jkl.png

A general replacement example:

rnm -rs '/a/AbracaDabra/' ./*

This will replace the first occurrence of an 'a' in the filenames with 'AbracaDabra'

Now the files look like:

AbracaDabrabc.jpg
AbracaDabrabc.png
def.jpg
def.png
ghi.jpg
ghi.png
jkl.jpg
jkl.png

2.1 Delete part of a filename:

To delete part of a filename we just need to replace that part with an empty string. Let's delete all d's from the filenames:

rnm -rs '/d//gi' ./*

Now the files look like:

Abracaabrabc.jpg
Abracaabrabc.png
ef.jpg
ef.png
ghi.jpg
ghi.png
jkl.jpg
jkl.png

We are selecting d and replacing it with empty string (delete operation). We have used two modifiers here: g and i. We already know that g is for global, and the newly introduced i is for case-insensitive search/selection. Thus you can see that the capital D in AbracaDabra is been deleted too.

2.2 Modify part of a filename:

Now let's delete Abrac and abra from the filenames and insert a d for the filenames starting with ef:

rnm -rs '/abrac//i;/abra//i;/^ef/d&/' ./*

Now the files look like:

abc.jpg
abc.png
def.jpg
def.png
ghi.jpg
ghi.png
jkl.jpg
jkl.png

As you have already noticed, -rs option can take multiple Replace Strings. Notice the Replace String: /^ef/d&/, the regex ^ef selects/matches ef at the beginning and replaces it with d and the match (& is the match found by the regex ^ef i.e ef itself).

2.3 Swap part of filenames with another part:

Let's swap the parts on either side of the dot (.) in each filename:

rnm -rs '/(.*)\.(.*)/\2.\1/' ./*

Now the state of files in our directory:

jpg.abc
jpg.def
jpg.ghi
jpg.jkl
png.abc
png.def
png.ghi
png.jkl

\n is the n'th back-reference, i.e \1 is the first captured group in the search/select/match regex (.*)\.(.*), and \2 is the second captured group.

2.4 Another replacement example:

We will now replace 'a' with 'AbracaDabra' but not all 'a'; only the files containing 'png' at first will be subject to this replacement:

rnm -rs '/(^png.*)a/\1AbracaDabra/' ./*

The files now:

jpg.abc
jpg.def
jpg.ghi
jpg.jkl
png.AbracaDabrabc
png.def
png.ghi
png.jkl

Yap, that's one file only. That file was the only one matching the regex (^png.*)a and we kept the (^png.*) part unchanged with the back-reference \.

2.5 Mixing with case-conversion:

Yes, you can mix other replacement methods with case-conversion too. Case-conversion is nothing but a specialized form of Replace String. Let's swap the two sides of the dot (.) once again and convert them to uppercase excluding extensions:

rnm -rs '/(.*)\.(.*)/\2.\1/;/.*\./\C/' ./*

The files now look like:

ABC.jpg
ABRACADABRABC.png
DEF.jpg
DEF.png
GHI.jpg
GHI.png
JKL.jpg
JKL.png

You may be wondering why the png and jpg were taken as extensions, they were at the beginning not at end. Yes that's right, but the first Replace String changed that order by swapping the two sides of the dot (.) i.e when the second Replace String were executed, it got the png and jpg as the file extensions.

N.B: the Name String Rule /e/ always contains the actual extension and /n/ always contains the actual filename without extension.

Let's see what happens if we use built-in filename extension support. First let's undo the last operation:

rnm -u

Files will look like:

jpg.abc
jpg.def
jpg.ghi
jpg.jkl
png.AbracaDabrabc
png.def
png.ghi
png.jkl

Now let's use /n/ for the filename without extension instead of the regex .*\. like the previous command:

rnm -rs '/(.*)\.(.*)/\2.\1/;//n//\C/' ./*

The files will look like:

abc.JPG
AbracaDabrabc.PNG
def.JPG
def.PNG
ghi.JPG
ghi.PNG
jkl.JPG
jkl.PNG

The actual filename-without-extension (left side of the dot) was jpg or png and thus those two are the only ones which got capitalized. The Name String Rule /n/ always contains the actual filename-without-extension no matter how many times replacement is occurred on the filename.

3 Indexing of files:

rnm provides certain Name String Rules for filename indexing. Name string rules are some predefined rules which provide some extended functionalities. Each of them has a unique definition and meaning and can be used in Replace String or Name String to generate new names for files. Name string is a string that simply implies a name for a file (Name String=name of file).

3.1 Insert general index in filenames:

/i/ is the Name String Rule for general indexing. Let's insert an index before the dot (.) in those files:

rnm -rs '//n//&/i//' ./*

The files now:

abc1.JPG
AbracaDabrabc2.PNG
def3.JPG
def4.PNG
ghi5.JPG
ghi6.PNG
jkl7.JPG
jkl8.PNG

Now, let's replace those indexes with better indexes:

rnm -rs '/\d//i//' -ifl 3 ./*

The files now:

abc001.JPG
AbracaDabrabc002.PNG
def003.JPG
def004.PNG
ghi005.JPG
ghi006.PNG
jkl007.JPG
jkl008.PNG

-ifl stands for index field length, empty field will be filled index field filler (defaults to 0).

Let's fill the empty field of indexes with other character than a zero (0). First undo rnm -u so that files look like:

abc1.JPG
AbracaDabrabc2.PNG
def3.JPG
def4.PNG
ghi5.JPG
ghi6.PNG
jkl7.JPG
jkl8.PNG

Now run command:

rnm -rs '/\d//i//' -ifl 3 -iff '*' ./*

Now the files look like:

abc**1.JPG
AbracaDabrabc**2.PNG
def**3.JPG
def**4.PNG
ghi**5.JPG
ghi**6.PNG
jkl**7.JPG
jkl**8.PNG

-iff stands for index field filler, empty field will be filled with specified character.

You want all the PNGs to be indexed first and JPGs second:

rnm -rs '/\d//i//' -ifl 3 *.PNG *.JPG

Files now:

abc**005.JPG
AbracaDabrabc**001.PNG
def**002.PNG
def**006.JPG
ghi**003.PNG
ghi**007.JPG
jkl**004.PNG
jkl**008.JPG

4 PNGs were indexed first.

Let's insert another index after the first letter in every filename:

rnm -rs '/./&/i//' -ifl 4 ./*

Files now:

a0001bc**005.JPG
A0002bracaDabrabc**001.PNG
d0003ef**002.PNG
d0004ef**006.JPG
g0005hi**003.PNG
g0006hi**007.JPG
j0007kl**004.PNG
j0008kl**008.JPG

Let's insert another index at the end:

rnm -rs '/$//i//' -ifl 5 ./*

Files now:

a0001bc**005.JPG00001
A0002bracaDabrabc**001.PNG00002
d0003ef**002.PNG00003
d0004ef**006.JPG00004
g0005hi**003.PNG00005
g0006hi**007.JPG00006
j0007kl**004.PNG00007
j0008kl**008.JPG00008

That's enough general indexing, let's get back our original files:

rnm -rs '/\d+//g;/\*+//g;/Abrac//;/Dabra//' ./*

Files now:

abc.JPG
abc.PNG
def.JPG
def.PNG
ghi.JPG
ghi.PNG
jkl.JPG
jkl.PNG

3.2 Insert directory-wise index in filenames:

The name string rule for directory-wise indexing is /id/. It is the same as /i/ except in every directory it is initialized to 1 or a user set value. It is useful if you rename files recursively in multiple directories. In every directory /id/ is reinitialized where /i/ always increases or decreases. To see it in action, let's create a directory named folder1 and copy the files there. Thus we have the same set of files in two directories.

Now, let's run an indexing command:

rnm -rs '/$//id//' -ifl 3 -fo -dp -1 ./*

Files:

./abc.JPG001
./abc.PNG002
./def.JPG003
./def.PNG004
./folder1/abc.JPG001
./folder1/abc.PNG002
./folder1/def.JPG003
./folder1/def.PNG004
./folder1/ghi.JPG005
./folder1/ghi.PNG006
./folder1/jkl.JPG007
./folder1/jkl.PNG008
./ghi.JPG005
./ghi.PNG006
./jkl.JPG007
./jkl.PNG008

-fo stands for file only mode. -dp stands for depth of directory. -1 makes unlimited depth i.e it will go through as many subdirectories there are. -dp without file only mode (-fo) is meaningless.

3.3 Set start index and/or end index for file indexing:

You can set an starting index from where the indexing will start and also an end index where the index will stop. When end index is reached it will stop renaming files.

Let's set an starting index of 50 and insert that index at the beginning of every file:

rnm -rs '/^//i//' -ifl 3 -si 50 -fo -dp -1 ./*

Files now:

./050abc.JPG001
./051abc.PNG002
./052def.JPG003
./053def.PNG004
./062ghi.JPG005
./063ghi.PNG006
./064jkl.JPG007
./065jkl.PNG008
./folder1/054abc.JPG001
./folder1/055abc.PNG002
./folder1/056def.JPG003
./folder1/057def.PNG004
./folder1/058ghi.JPG005
./folder1/059ghi.PNG006
./folder1/060jkl.JPG007
./folder1/061jkl.PNG008

-si or -i stands for starting index.

Let's set an starting index of 40 and end index of 44 and see what happens:

rnm -rs '/^//id//' -ifl 3 -i 40 -ei 44 -fo -dp -1 ./*

Files now:

./040050abc.JPG001
./041051abc.PNG002
./042052def.JPG003
./043053def.PNG004
./044062ghi.JPG005
./045063ghi.PNG006
./046064jkl.JPG007
./047065jkl.PNG008
./folder1/040054abc.JPG001
./folder1/041055abc.PNG002
./folder1/042056def.JPG003
./folder1/043057def.PNG004
./folder1/044058ghi.JPG005
./folder1/059ghi.PNG006
./folder1/060jkl.JPG007
./folder1/061jkl.PNG008

As you can see, the end index only worked inside the directory. When you pass files with filename globbing like ./* or *, every files and directories are passed as each arguments and each argument for rnm is important and thus rnm doesn't skip any of them, not even if the index ends. The end index is valid only for files which are inside a directory that has been passed as a command line argument or taken recursively by rnm itself. In a nut-shell, end index works on directory index only.

3.4 Reserve index for skipped files:

Some files may be skipped for various reasons. Also you can manually skip a file from renaming. In these cases the index for that file is not reserved i.e the index of that file is given to the next file. But there's a name string rule which keeps track of these indexes. These indexes are called reserved indexes. To form a name string rule that reserves indexes for skipped file simply add a r at the end of the index name in a Name String Rule. For example, /i/ to /ir/, /id/ to /idr/ etc...

Let's see it in action:

rnm -sim -f -ns '/ir/' /*

/bin    ---->    /1

Select action:

    1. Confirm for this file only.
    2. Confirm for all.
    3. Skip this file.
    4. Skip all and exit

Your choice: 3

/boot    ---->    /2

Select action:

    1. Confirm for this file only.
    2. Confirm for all.
    3. Skip this file.
    4. Skip all and exit

Your choice: 3

/cdrom    ---->    /3

Select action:

    1. Confirm for this file only.
    2. Confirm for all.
    3. Skip this file.
    4. Skip all and exit

Your choice:

We have used the / directory here. Don't worry, it's perfectly safe. The -sim option runs a simulation (not actual rename). Just note the fact that even if the files are skipped, the index continues to increase i.e those indexes are being reserved for those skipped files/directories. -ns is name string (simply name of file).

3.5 Negative indexing of files (Decremented index):

A minus sign (-) inside Name string rule implies negative index. The -ve of /i/ is /-i/, -ve of /id/ is /-id/ etc.. More appropriately it's decremented index.

rnm -ifl 2 -rs '/^//-id//' ./*

Files now:

-01040050abc.JPG001
-02041051abc.PNG002
-03042052def.JPG003
-04043053def.PNG004
-05044062ghi.JPG005
-06045063ghi.PNG006
-07046064jkl.JPG007
-08047065jkl.PNG008
-09folder1

Note that, it didn't go inside the directory, instead it renamed the directory itself.

3.6 Configure increment value for file indexing:

You can configure the increment value of the index with the -inc option. It can take floating point decimal +ve number. -ve number is not allowed because decremented index will be available through name string rules /-i/, /-id/ etc.

Let's set increment of 4 starting from 6.

rnm -rs '/-\d+//id//' -inc 4 -si 6 ./*

Files now:

6abc.JPG001
10abc.PNG002
14def.JPG003
18def.PNG004
22ghi.JPG005
26ghi.PNG006
30jkl.JPG007
34jkl.PNG008
38folder1

Let's set the increment value at 4.5 and start from 6:

rnm -rs '/\d+//id//' -inc 4.5 -si 6 ./*

Files now:

6abc.PNG002
10.5def.JPG003
15def.PNG004
19.5ghi.JPG005
24ghi.PNG006
28.5jkl.JPG007
33jkl.PNG008
37.5folder1
42abc.JPG001

4 Search for files and rename:

rnm has built-in search functionality. It uses regex or fixed string to search for files/directories. The -ss and -ssf option takes search strings. -ss is for regex search and -ssf is for fixed string search.

4.1 Search for files with regex and rename:

Let's apply rename if only some specific string exists in the filename. We will rename those files which starts with a 1 at the beginning:

Current state of files:

6def.PNG004
11ghi.JPG005
15ghi.PNG006
20jkl.JPG007
24jkl.PNG008
29abc.JPG001
33abc.PNG002
38folder1
42def.JPG003

Let's run the command:

rnm -rs '/\d+\.?\d*//' -ss '^1' ./*

Files now:

ghi.JPG005
ghi.PNG006
6def.PNG004
20jkl.JPG007
24jkl.PNG008
29abc.JPG001
33abc.PNG002
38folder1
42def.JPG003

4.2 Search for files with fixed strings and rename:

For fixed string search we will use the -ssf option.

rnm -rs '/\d+\.?\d*//' -ssf '.' ./*

Files now:

abc.JPG001
abc.PNG002
def.JPG003
def.PNG004
ghi.JPG
ghi.PNG
jkl.JPG007
jkl.PNG008
38folder1

Dot (.) matches any character when used as regex. But as a fixed string it's just dot. The 38folder1 doesn't contain any dot and thus skipped.

4.3 Search for files with multiple search strings and rename:

The option -ss or -ssf can take multiple search strings. In such cases search strings are to be wrapped around with / and terminated with semicolon (;).

rnm -rs '/\d+\.?\d*//' -ssf '/./;/8/' ./*
abc.JPG
abc.PNG
def.JPG
def.PNG
folder1
ghi.JPG
ghi.PNG
jkl.JPG
jkl.PNG

4.4 Search for files with case-insensitive search and rename:

For case insensitive search we can use a modifier (i). To use modifier search strings are to be wrapped around with /.

rnm -rs '/.//i/&/' -ss '/A/i' ./*

Files now:

def.JPG
def.PNG
folder1
ghi.JPG
ghi.PNG
jkl.JPG
jkl.PNG
1abc.JPG
2abc.PNG

Even though we searched for capital 'A', it worked on small 'a' because of the case-insensitive search.