change all file names (prefix to postfix)

Question

I have a directory containing thousands of files with names

t_00xx_000xxx.png

I want to change their names to 00xx_000xxx_t.png

so take the prefix and put it as a postfix, can this be done in only one command

Answer 1

This is possible with the rename command:

First check what would be done (by suppliying -n). If it looks good, drop the -n and run again:

rename -n 's/t_(.+)\.png$/$1_t.png/' *.png  # check only
rename    's/t_(.+)\.png$/$1_t.png/' *.png  # actually rename the files

Answer 2

If the prefix is separated by an underscore (_), you can do the following:

rename -n 's/^([^_]*)_(.*)\.(.*)$/$2_$1.$3/' file(s)

It will work with any prefix and any extension.

Remove the -n to perform the rename if you're happy with the result.

---

Explanation:

• s/search_pattern/replace_pattern/

Search pattern:

• ^ - Match the beginning of the file name
• ([^_]*) - Match any character that is not an underscore [^_]* and capture it as $1 (...)
• _ - Match the first underscore
• (.*)\.(.*) - Match anything .* before and after the last . and capture it as $2 and $3. The . must be escaped because it is a special character in Regex --> \.
• $ - Match the end of the line

Replace pattern:

• $2_$1.$3 - "Filename_Prefix.Extension" from the search pattern captures.

Answer 3

mmv (available from the universe repository) is nice for this kind of thing, where simple shell globs rather than regular expression can do the job

Ex.

mmv -n -- '*_*_*.png' '#2_#3_#1.png'
t_00xx_000xxx.png -> 00xx_000xxx_t.png

Remove the -n once you are happy that it's working right.