How do I rename the extension for a bunch of files?

If using bash, there's no need for external commands like sed, basename, rename, expr, etc.

for file in *.html
do
  mv "$file" "${file%.html}.txt"
done

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For an better solution (with only bash functionality, as opposed to external calls), see one of the other answers.

The following would do and does not require the system to have the rename program (although you would most often have this on a system):

for file in *.html; do
    mv "$file" "$(basename "$file" .html).txt"
done

EDIT: As pointed out in the comments, this does not work for filenames with spaces in them without proper quoting (now added above). When working purely on your own files that you know do not have spaces in the filenames this will work but whenever you write something that may be reused at a later time, do not skip proper quoting.

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rename 's/\.html$/\.txt/' *.html

does exactly what you want.

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This worked for me on OSX from .txt to .txt_bak

find . -name '*.txt' -exec sh -c 'mv "$0" "${0%.txt}.txt_bak"' {} \;

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You want to use rename :

rename -S <old_extension> <new_extension> <files>

rename -S .html .txt *.html

This does exactly what you want - it will change the extension from .html to .txt for all files matching *.html.

Note: Greg Hewgill correctly points out this is not a bash builtin; and is a separate Linux command. If you just need something on Linux this should work fine; if you need something more cross-platform then take a look at one of the other answers.

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On a Mac...

Install rename if you haven't: brew install rename rename -S .html .txt *.html

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For Ubuntu Users :

rename 's/\.html$/\.txt/' *.html

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This is the slickest solution I've found that works on OSX and Linux, and it works nicely with git too!

find . -name "*.js" -exec bash -c 'mv "$1" "${1%.js}".tsx' - '{}' \;

and with git:

find . -name "*.js" -exec bash -c 'git mv "$1" "${1%.js}".tsx' - '{}' \;

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This question explicitly mentions Bash, but if you happen to have ZSH available it is pretty simple:

zmv '(*).*' '$1.txt'

If you get zsh: command not found: zmv then simply run:

autoload -U zmv

And then try again.

Thanks to this original article for the tip about zmv.

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Here is an example of the rename command:

rename -n ’s/\.htm$/\.html/’ *.htm

The -n means that it's a test run and will not actually change any files. It will show you a list of files that would be renamed if you removed the -n. In the case above, it will convert all files in the current directory from a file extension of .htm to .html.

If the output of the above test run looked ok then you could run the final version:

rename -v ’s/\.htm$/\.html/’ *.htm

The -v is optional, but it's a good idea to include it because it is the only record you will have of changes that were made by the rename command as shown in the sample output below:

$ rename -v 's/\.htm$/\.html/' *.htm
3.htm renamed as 3.html
4.htm renamed as 4.html
5.htm renamed as 5.html

The tricky part in the middle is a Perl substitution with regular expressions, highlighted below:

rename -v ’s/\.htm$/\.html/’ *.htm

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One line, no loops:

ls -1 | xargs -L 1 -I {} bash -c 'mv $1 "${1%.*}.txt"' _ {}

Example:

$ ls
60acbc4d-3a75-4090-85ad-b7d027df8145.json  ac8453e2-0d82-4d43-b80e-205edb754700.json
$ ls -1 | xargs -L 1 -I {} bash -c 'mv $1 "${1%.*}.txt"' _ {}
$ ls
60acbc4d-3a75-4090-85ad-b7d027df8145.txt  ac8453e2-0d82-4d43-b80e-205edb754700.txt

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The command mmv seems to do this task very efficiently on a huge number of files (tens of thousands in a second). For example, to rename all .xml files to .html files, use this:

mmv ";*.xml" "#1#2.html"

the ; will match the path, the * will match the filename, and these are referred to as #1 and #2 in the replacement name.

Answers based on exec or pipes were either too slow or failed on a very large number of files.

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Try this

rename .html .txt *.html 

usage:

rename [find] [replace_with] [criteria]

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After someone else's website crawl, I ended up with thousands of files missing the .html extension, across a wide tree of subdirectories.

To rename them all in one shot, except the files already having a .html extension (most of them had none at all), this worked for me:

cd wwwroot
find . -xtype f \! -iname *.html   -exec mv -iv "{}"  "{}.html"  \;  # batch rename files to append .html suffix IF MISSING

In the OP's case I might modify that slightly, to only rename *.txt files, like so:

find . -xtype f  -iname *.txt   -exec filename="{}"  mv -iv ${filename%.*}.{txt,html}  \; 

Broken down (hammertime!):

-iname *.txt - Means consider ONLY files already ending in .txt

mv -iv "{}.{txt,html}" - When find passes a {} as the filename, ${filename%.*} extracts its basename without any extension to form the parameters to mv. bash takes the {txt,html} to rewrite it as two parameters so the final command runs as: mv -iv "filename.txt" "filename.html"

Fix needed though: dealing with spaces in filenames

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This is a good way to modify multiple extensions at once:

for fname in *.{mp4,avi}
do
   mv -v "$fname" "${fname%.???}.mkv"
done

Note: be careful at the extension size to be the same (the ???)

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In Linux or window git bash or window's wsl, try below command to change every file's extension in current directory or sub-directories or even their sub-directories with just one line of code

find . -depth -name "*.html" -exec sh -c 'mv "$1" "${1%.html}.txt"' _ {} \;

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A bit late to the party. You could do it with xargs:

ls *.html | xargs -I {} sh -c 'mv $1 `basename $1 .html`.txt' - {}

Or if all your files are in some folder

ls folder/*.html | xargs -I {} sh -c 'mv $1 folder/`basename $1 .html`.txt' - {}

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Similarly to what was suggested before, this is how I did it:

find . -name '*OldText*' -exec sh -c 'mv "$0" "${0/OldText/NewText}"' {} \;

I first validated with

find . -name '*OldText*' -exec sh -c 'echo mv "$0" "${0/OldText/NewText}"' {} \;

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Rename file extensions for all files under current directory and sub directories without any other packages (only use shell script):

Create a shell script rename.sh under current directory with the following code: #!/bin/bash for file in $(find . -name "*$1"); do mv "$file" "${file%$1}$2" done Run it by ./rename.sh .old .new. Eg. ./rename.sh .html .txt

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Nice & simple!

find . -iname *.html  -exec mv {} "$(basename {} .html).text"  \;

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If you prefer PERL, there is a short PERL script (originally written by Larry Wall, the creator of PERL) that will do exactly what you want here: tips.webdesign10.com/files/rename.pl.txt.

For your example the following should do the trick:

rename.pl 's/html/txt/' *.html

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Here is what i used to rename .edge files to .blade.php

for file in *.edge; do     mv "$file" "$(basename "$file" .edge).blade.php"; done

Works like charm.

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You can also make a function in Bash, add it to .bashrc or something and then use it wherever you want.

change-ext() {
    for file in *.$1; do mv "$file" "$(basename "$file" .$1).$2"; done
}

Usage:

change-ext css scss

Source of code in function: https://stackoverflow.com/a/1224786/6732111

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The easiest way is to use rename.ul it is present in most of the Linux distro

rename.ul -o -v [oldFileExtension] [newFileExtension] [expression to search for file to be applied with]

rename.ul -o -v .oldext .newext *.oldext

Options:

-o: don't overwrite preexisting .newext

-v: verbose

-n: dry run

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Unfortunately it's not trivial to do portably. You probably need a bit of expr magic.

for file in *.html; do echo mv -- "$file" "$(expr "$file" : '\(.*\)\.html').txt"; done

Remove the echo once you're happy it does what you want.

Edit: basename is probably a little more readable for this particular case, although expr is more flexible in general.

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Here is a solution, using AWK. Make sure the files are present in the working directory. Else, cd to the directory where the html files are located and then execute the below command:

for i in $(ls | grep .html); do j=$(echo $i | grep -oh "^\w*." | awk '{print $1"txt"}'); mv $i $j; done

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I wrote this code in my .bashrc

alias find-ext='read -p "Path (dot for current): " p_path; read -p "Ext (unpunctured): " p_ext1; find $p_path -type f -name "*."$p_ext1'
alias rename-ext='read -p "Path (dot for current): " p_path; read -p "Ext (unpunctured): " p_ext1; read -p "Change by ext. (unpunctured): " p_ext2; echo -en "\nFound files:\n"; find $p_path -type f -name "*.$p_ext1"; find $p_path -type f -name "*.$p_ext1" -exec sh -c '\''mv "$1" "${1%.'\''$p_ext1'\''}.'\''$p_ext2'\''" '\'' _ {} \;; echo -en "\nChanged Files:\n"; find $p_path -type f -name "*.$p_ext2";'

In a folder like "/home//example-files" having this structure:

/home//example-files: file1.txt file2.txt file3.pdf file4.csv

file1.txt

file2.txt

file3.pdf

file4.csv

The commands would behave like this:

~$ find-text
Path (dot for current): example-files/
Ext (unpunctured): txt

example-files/file1.txt
example-files/file2.txt


~$ rename-text
Path (dot for current): ./example-files
Ext (unpunctured): txt
Change by ext. (unpunctured): mp3

Found files:
./example-files/file1.txt
./example-files/file1.txt

Changed Files:
./example-files/file1.mp3
./example-files/file1.mp3
~$

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You could use a tool designed for renaming files in bulk, e.g. renamer.

To rename all file extensions in the current folder:

$ renamer --find ".html" --replace ".txt" --dry-run * 

Many more usage examples here.

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