How to use sed to change file extensions?

Question

I have to do a sed line (also using pipes in Linux) to change a file extension, so I can do some kind of mv *.1stextension *.2ndextension like mv *.txt *.c. The thing is that I can't use batch or a for loop, so I have to do it all with pipes and sed command.

Why you can't use loop ? You should make it clear ! Are you doing this as a part of a homework ? — iamauser, Oct 03 '13 at 17:38
of course i am, i didn't mentioned but i think it's pretty known because of teh restrictions — heythatsmekri, Oct 05 '13 at 21:38

CS Pei · Answer 1 · 2018-01-12T02:56:20.813

12

you can use string manipulation

filename="file.ext1"
mv "${filename}" "${filename/%ext1/ext2}"

Or if your system support, you can use rename.

Update

you can also do something like this

mv ${filename}{ext1,ext2}

which is called brace expansion

edited Jan 12 '18 at 02:56

answered Oct 03 '13 at 17:07

CS Pei

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I wonder if we are allowed to user `rename` ...it is available in most Linux system – CS Pei Oct 03 '13 at 17:19
Thanks, but i cant use any batch or script sentence, I just can use my command line, sed and pipes – heythatsmekri Oct 03 '13 at 17:22
what exactly your input? what kind of output do you expect? if only `sed` allowed I don't think you can rename a file. – CS Pei Oct 03 '13 at 17:25
2

@user2113403: `for filename in *.1stextension; do mv "${filename}" "${filename/%1stextension/2ndextension}"; done` will do for a bunch of files. No need for `sed`. – bitmask Oct 03 '13 at 19:44
POSIX: `${filename%.ext1}.ext2` – OJFord Jan 14 '17 at 18:59

score 5 · Answer 2 · edited May 23 '17 at 10:29

5

sed is for manipulating the contents of files, not the filename itself. My suggestion:

rename 's/\.ext/\.newext/' ./*.ext

Or, there's this existing question which should help.

edited May 23 '17 at 10:29

Community

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answered Oct 03 '13 at 17:54

chooban

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I had to substitute .c with .o in a Makefile. This solved my problem, thanks. – Garini Jul 06 '17 at 17:04

score 4 · Answer 3 · edited Jun 19 '17 at 00:51

4

This may work:

find . -name "*.txt" | 
sed -e 's|./||g' | 
awk '{print "mv",$1, $1"c"}' | 
sed -e "s|\.txtc|\.c|g" > table;
chmod u+x table;
./table

I don't know why you can't use a loop. It makes life much easier :

newex="c";  # Give your new extension
for file in *.*;  # You can replace with *.txt instead of *.*
do 
 ex="${file##*.}";    # This retrieves the file extension
 ne=$(echo "$file" | sed -e "s|$ex|$newex|g"); # Replaces current with the new one
 echo "$ex";echo "$ne";
 mv "$file" "$ne";
done

edited Jun 19 '17 at 00:51

agc

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answered Oct 03 '13 at 17:16

iamauser

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I'm supposed not to use any loop or sentence, just pipes, comand line and sed – heythatsmekri Oct 03 '13 at 17:21

David W. · Answer 4 · 2015-01-07T16:01:24.393

3

You can use find to find all of the files and then pipe that into a while read loop:

$ find . -name "*.ext1" -print0 | while read -d $'\0' file
do
   mv $file "${file%.*}.ext2"
done

The ${file%.*} is the small right pattern filter. The % marks the pattern to remove from the right side (matching the smallest glob pattern possible), The .* is the pattern (the last . followed by the characters after the .).

The -print0 will separate file names with the NUL character instead of \n. The -d $'\0' will read in file names separated by the NUL character. This way, file names with spaces, tabs, \n, or other wacky characters will be processed correctly.

edited Jan 07 '15 at 16:01

answered Oct 03 '13 at 17:23

David W.

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How this is not a loop ? OP doesn't want any loop ! – iamauser Oct 03 '13 at 17:24
It's a pipe. As the OP said "_so i have to do it all with **pipes** and sed command_". I'm not sure what the issue the OP was having with `for`, but `for` can be troublesome because of the way it parses the parameters for the loop. Unfortunately, the OP didn't provide much information what they are doing. With more info, I could give a better answer. – David W. Oct 03 '13 at 17:33
Agree with you that OP doesn't provide enough information, why not loop ! – iamauser Oct 03 '13 at 17:45

jkshah · Answer 5 · 2013-10-03T17:54:33.450

2

You may try following options

Option 1 find along with rename

find . -type f -name "*.ext1" -exec rename -f 's/\.ext1$/ext2/' {} \;

Option 2 find along with mv

find . -type f -name "*.ext1" -exec sh -c 'mv -f $0 ${0%.ext1}.ext2' {} \;

Note: It is observed that rename doesn't work for many terminals

edited Oct 03 '13 at 17:54

answered Oct 03 '13 at 17:46

jkshah

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@iamauser try using option 2 `mv` if `rename` is not working. Even I am not sure why `rename` doesn't work for many terminals. For me it works in `ubuntu` but not in `RHEL` – jkshah Oct 03 '13 at 17:51

score 2 · Answer 6 · edited Jun 19 '17 at 00:50

2

Another solution only with sed and sh

printf "%s\n" *.ext1 | 
sed "s/'/'\\\\''/g"';s/\(.*\)'ext1'/mv '\''\1'ext1\'' '\''\1'ext2\''/g' | 
sh

for better performance: only one process created

perl -le '($e,$f)=@ARGV;map{$o=$_;s/$e$/$f/;rename$o,$_}<*.$e>' ext2 ext3

edited Jun 19 '17 at 00:50

agc

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answered Oct 03 '13 at 19:40

Nahuel Fouilleul

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score 0 · Answer 7 · answered Aug 02 '21 at 10:22

0

well this should work

mv $file $(echo $file | sed -E -e 's/.xml.bak.*/.xml/g' | sed -E -e 's/.\///g')

output

abc.xml.bak.foobar -> abc.xml

answered Aug 02 '21 at 10:22

Abhiroj Panwar

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How to use sed to change file extensions?

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