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I have many files with .abc extension and want to change them to .edefg
How to do this from command line ?

EDIT: I have a root folder with many sub-folders, so the solution should work -r recursively.

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See askubuntu.com/questions/10607/… –  belacq Apr 19 '11 at 22:11

4 Answers 4

A portable way (which will work on any POSIX compliant system):

find /the/path -depth -name "*.abc" -exec sh -c 'mv "$1" "${1%.abc}.edefg"' _ {} \;

In bash4, you can use globstar to get recursive globs (**):

shopt -s globstar
for file in /the/path/**/*.abc; do
  mv "$file" "${file%.abc}.edefg"
done

The (perl) rename command in ubuntu can rename files using perl regular expression syntax, which you can combine with globstar or the find command:

# Using globstar
shopt -s globstar
files=(/the/path/**/*.abc)  

# Best to process the files in chunks to avoid exceeding the maximum argument 
# length. 100 at a time is probably good enough. 
# See http://mywiki.wooledge.org/BashFAQ/095
for ((i = 0; i < ${#files[@]}; i += 100)); do
  rename 's/\.abc$/.edefg/' "${files[@]:i:100}"
done

# Using find:
find /the/path -depth -name "*.abc" -exec rename 's/\.abc$/.edefg/' {} +

Also see http://mywiki.wooledge.org/BashFAQ/030

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the first one simply appends the new extension onto the old one, it doesn't replace... –  user2757729 May 21 at 15:35
    
@user2757729, it does replace it. "${1%.abc}" expands to the value of $1 except without .abc at the end. See faq 100 for more on shell string manipulations. –  geirha May 22 at 8:51
    
I ran this on a ~70k files file structure... at least on my shell it most definitely did not replace it. –  user2757729 May 22 at 15:52
    
Sorry just set up a test dir structure and it seems to be working. Wonder what I did wrong yesterday. –  user2757729 May 22 at 15:56

This will do the required task if all the files are in the same folder

rename 's/.abc$/.edefg/' *.abc

To rename the files recursively use this:

find /path/to/root/folder -type f -name '*.abc' -print0 | xargs -0 rename 's/.abc$/.edefg/'
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4  
Or rename 's/.abc$/.edefg/' /path/to/root/folder/**/*.abc in a modern version of Bash. –  Adam Byrtek Apr 19 '11 at 18:35
    
Great thanks Adam for giving me a tip on how to use *.abc in folders recursively! –  Rafał Cieślak Apr 19 '11 at 18:42
    
Great tip, thanks ! Where can I find more documentation about the little piece of regex's syntax ? Like what's the s at the beginning, and what other options can I use in there. Thanks ! –  Anto Mar 8 '13 at 1:23
    
Thanks this one worked great for me. –  user2757729 May 21 at 15:42

One problem with recursive renames is that whatever method you use to locate the files, it passes the whole path to rename, not just the file name. That makes it hard to do complex renames in nested folders.

I use find's -execdir action to solve this problem. If you use -execdir instead of -exec, the specified command is run from the subdirectory containing the matched file. So, instead of passing the whole path to rename, it only passes ./filename. That makes it much easier to write the regex.

find /the/path -type f \
               -name '*.abc' \
               -execdir rename 's/\.\/(.+)\.abc$/version1_$1.abc/' {} \;

In detail:

  • -type f means only look for files, not directories
  • -name '*.abc' means means only match filenames that end in .abc
  • The backslashes after -type and -name are the bash line-continuation character. I use them to make this example more readable, but they are not needed in practice.
  • However, the backslash at the end of the -execdir line is required. It is there to esacpe the semicolon, which terminates the command run by -execdir. Fun!

Explanation of the regex:

  • s/ start of the regex
  • \.\/ match the leading ./ that -execdir passes in. Use \ to escape the . and / metacharacters
  • (.+) match the filename. The parentheses capture the match for later use
  • \.abc escape the dot, match the abc
  • $ anchor the match at the end of the string

  • / marks the end of the "match" part of the regex, and the start of the "replace" part

  • version1_ add this text to every file name

  • $1 references the existing filename, because we captured it with parentheses. If you use multiple sets of parentheses in the "match" part, you can refer to them here using $2, $3, etc.
  • .abc the new file name will end in .abc. No need to escape the dot metacharacter here in the "replace" section
  • / end of the regex

Before

tree --charset=ascii

|-- a_file.abc
|-- Another.abc
|-- Not_this.def
`-- dir1
    `-- nested_file.abc

After

tree --charset=ascii

|-- version1_a_file.abc
|-- version1_Another.abc
|-- Not_this.def
`-- dir1
    `-- version1_nested_file.abc

Hint: rename's -n option is useful. It does a dry run and shows you what names it will change, but does not make any changes.

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Another portable way:

find /the/path -depth -type f -name "*.abc" -exec sh -c 'mv "$1" "$(dirname "$1")/$(basename "$1" .abc).edefg"' _ {} \;
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4  
Welcome to Ask Ubuntu! While this is a valuable answer, I recommend expanding it (by editing) to explain how and why that command works. –  Eliah Kagan Feb 3 '13 at 16:44

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