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What is the good way to add file extension ".jpg" to extension-less files with bash?

Nakilon
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Adrian
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10 Answers10

148
# Strip .jpg from all filenames
for f in *.jpg; do mv "$f" "${f%.jpg}"; done
# Add .jpg to all filenames (even those with .jpg already)
for f in *; do mv "$f" "$f.jpg"; done
# Add .jpg to all filenames...unless they are already .jpg
for f in *; do case "$f" in *.jpg) echo skipped $f;; *) mv "$f" "$f".jpg; esac; done
# Add .jpg to all filenames...unless they already have a . extension
for f in *; do case "$f" in *.*) echo skipped $f;; *) mv "$f" "$f".jpg; esac; done
Seth Robertson
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67

You can use rename:

rename 's/(.*)/$1.jpg/' *
Kim Stebel
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30

Another way - without loops

find . -type f -not -name "*.*" -print0 |\
xargs -0 file |\
grep  'JPEG image data' |\
sed 's/:.*//' |\
xargs -I % echo mv % %.jpg

Breakdown:

  • find all files without extension
  • check the file type
  • filter out only JPG files
  • delete filetype info
  • xargs run the "mv" for each file

the above command is for dry run, after it you should remove the "echo" before mv

EDIT Some people suggesting that here is needed "Wrap path arguments in quotes; avoids argument splitting on paths with spaces".

Usually, this recommendation is true, in this case isn't. Because, here the % is got replaced not by shell expansion but by the xargs internally (directly), so the % will be substituted correctly even with spaces in filenames.

Simple demo:

$ mkdir xargstest
$ cd xargstest

# create two files with spaces in names
$ touch 'a b' 'c d'

$ find . -type f -print
./c d
./a b
# notice, here are spaces in the above paths

#the actual xargs mv WITHOUT quotes
$ find . -type f -print | xargs -I % mv % %.ext

$ find . -type f -print
./a b.ext
./c d.ext
# the result is correct even in case with spaces in the filenames...
clt60
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  • You can put this into a loop and this xargs are superfluous. I like Ryan's answer better in this situation. – Lucius May 24 '11 at 19:51
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    @Lucius - btw, the question want "extensionless" files - so Ryan should find only those... – clt60 May 24 '11 at 20:12
  • @jm666 hey! how do I modify your code snippet to rename all extensionless files in a folder to their respective extensions. (I am detecting correct extensions by file -b $filename command.) – Soumyajit Jan 10 '16 at 16:44
26

Simple, cd to the directory where your files are and:

for f in *;do mv $f $f.jpg;done
bharath
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  • For some reason this works for me, but Seth's solution with quotes doesn't. (OSX Mountain Lion bash) – delrocco Dec 18 '16 at 14:36
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    Would be better if used `for f in *;do mv "$f" "$f".jpg;done` to support spaces in filenames. – Hritik Jun 22 '17 at 17:09
  • Thanks for this elegant and simple solution -- I have landed on this answer multiple times, but can't seem to memorize it. #dejavu – Tim Andersen Jan 30 '19 at 18:11
19

dry run:

 rename -n s/$/.jpg/ *

actual renaming:

 rename s/$/.jpg/ *
Melebius
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Alexey
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  • Beware that there isn't a single `rename` tool: https://oylenshpeegul.typepad.com/blog/2011/12/a-tale-of-two-renames.html – waldyrious Nov 18 '21 at 17:03
6
find . | while read FILE; do if [ $(file --mime-type -b "$FILE") == "image/jpeg" ]; then mv "$FILE" "$FILE".jpg; fi; done;
scottclowe
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Ryan Li
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1

In my case i was not aware of the filetype so i used the mv command with the help of the file command to examine and possibly find the file type. This solution might not be perfect for all files since the file command might not recognize the filetype but it worked mostly good for me.

for f in *; do ext=$(file $f | awk '{print $2;}'); mv -n "$f" "$f.$ext"; done

The use of awk is to strip the second word of the string returned from the command file that is actually the extension.

Paolo
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  • handles jpg and png automatically. used it and works - thanks a lot! Only now extensions are CAPS. small problem though :) – krivar Jul 14 '20 at 13:12
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rename --dry-run * -a ".jpg" # test  
* -a ".jpg" # rename
Roman Rhrn Nesterov
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  • `--dry-run` and `-a` are not available in my version of `rename`. If this is specific to some architecture it should be specified. – Fernando César Apr 09 '17 at 09:59
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    As @FernandoCésar alludes to, there isn't a single `rename` tool, so the syntax may vary in different systems. See https://oylenshpeegul.typepad.com/blog/2011/12/a-tale-of-two-renames.html for more information. – waldyrious Nov 18 '21 at 17:04
0

You can use move multiple files. I am a maintainer of this project. The syntax is simple.

mmf files*

It will open your $EDITOR with all files names, or vim by default and you can simply highlight the end of all file names using Ctrl+v+G in vim , save the file,quit and that it , all your files are renamed

Almas Abdrazak
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-3

Ryan Li

The correct syntax for adding a file extension to multiple files within a directory which do not have a file extension is 

find . | while read FILE; do if [[ -n `file --mime-type "$FILE" | grep 'message/rfc822'` ]]; then  mv "$FILE" "$FILE".eml; fi; done;
Dillon Beresford
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