How can I rename files in directory, while keeping part of the name unchanged?

Question

I have multiple files (about 1000) named as such:

abcdefg123456.xyz
abcdefg123457.xyz
abcdefg123458.xyz
abcdefg123459.xyz

Some of the files have 4 additional random numbers and letters (in any order) after the name. These are possibly duplicates, but not always, so I need to change them to the original format to verify whether they are duplicate or not. They have this format:

abcdefg123456a789.xyz
abcdefg123457b987.xyz
abcdefg123458c879.xyz
abcdefg123459d897.xyz

On occasion, there is a wrong extension as well,

abcdefg123456.xyzedf
abcdefg123456.xyzfed

I want to rename these files to the original format of abcdefg followed by the original 6 numbers - i.e. to delete the trailing 4 random numbers and letters, and to delete the trailing extension back .xyz What I have so far is this:

rename -n "s/[a-z][0-9]{6}.xyz/.xyz/g"  *

But it doesn't seem to work. For some reason the output is:

abcdef.xyz (no numbers)

EDIT: I was a bit torn between which answer to choose from, because both helped in finding the solution. I went for stuts because he helped with the second part of the question as well. But your help is greatly appreciated too Mark Perryman - and the commenters as well of course.

Answer 1

Solution

To remove the 4 numbers/letters preceding the full stop for all files you can use the following loop:

for file in *.xyz ; do
    NEWFILE=$(echo "$file" |sed -re 's/[a-z|0-9][a-z|0-9][a-z|0-9][a-z|0-9](\.)/\./g')
    mv -v $file $NEWFILE
done

Explanation

for file in *.xyz ; do

Loops through every file with a .xyz extension

NEWFILE=$(echo "$file" |sed -re 's/[a-z|0-9][a-z|0-9][a-z|0-9][a-z|0-9](\.)/\./g')

Create a variable called NEWFILE containing the name of the file after stripping out a pattern that matches [a-z|0-9][a-z|0-9][a-z|0-9][a-z|0-9] (a mix of 4 numbers or letters)and is followed by a full stop ((\.)).

mv -v $file $NEWFILE

Move the file to its new name, the -v will print the move process in the following format

`abcdefg123456a789.xyz` -> `abcdefg123456.xyz`

This currently does not cover the fixing of extensions but a similar solution to the above can be used but with the sed command being sed 's/\.xyz.*/\.xyz/g'.

Answer 2

Try

rename -n -f 's/([a-z]*[0-9]{6})[a-z0-9]{0,4}(\.xyz).*/$1$2/g'  *

This works on the version of rename released with debian and ubuntu (see man page at http://www.computerhope.com/unix/rename.htm)

This will overwrite files that would otherwise have duplicate names.

Why this works

• ([a-z]*[0-9]{6}) is the abcdefg123456 captured and can be referred to as $1 in the replacement.
• (\.xyz) is the extension captured and referred to as $2 in the replacement.
• Everything else [a-z0-9]{0,4} (up to 4 letters/numbers) and .* (anything after the extension) is matched and then ignored in the replacement.

Bonus To delete all files that still don't fit your pattern (e.g. if you did not use the force option above) then use find to list them and remove them. (Run without -exec rm {} for a dry run.)

find . -regextype posix-egrep -regex '.*/[a-z]*[0-9]{6}[a-z0-9]{4}\.xyz.*|[a-z]*[0-9]{6}\.xyz.*' -exec rm {}