Batch renaming files with a modification time restriction

Question

I wish to rename multiple (many) files, according to their modification datetime. That is, I wish to provide a date (say, 2014-31-03), and for that date, replace the substring a to the substring bc in any of the files whose modification date was that date.

For example, suppose the output of ls -latr --time-style=long-iso is as follows:

total 8
drwxrwxr-x 3 bach bach 4096 2014-04-01 10:02 ..
-rw-rw-r-- 1 bach bach    0 2014-03-31 10:02 a.1
-rw-rw-r-- 1 bach bach    0 2014-03-31 10:02 a.2
-rw-rw-r-- 1 bach bach    0 2014-03-31 10:02 bc.1
-rw-rw-r-- 1 bach bach    0 2014-04-01 10:02 a.3
-rw-rw-r-- 1 bach bach    0 2014-04-01 10:02 bc.2
-rw-rw-r-- 1 bach bach    0 2014-04-01 10:02 bc.3
drwxrwxr-x 2 bach bach 4096 2014-04-01 10:08 .

then the output after the modification should be as follows:

total 8
drwxrwxr-x 3 bach bach 4096 2014-04-01 10:02 ..
-rw-rw-r-- 1 bach bach    0 2014-03-31 10:02 bc.1
-rw-rw-r-- 1 bach bach    0 2014-04-01 10:02 a.3
-rw-rw-r-- 1 bach bach    0 2014-04-01 10:02 bc.2
-rw-rw-r-- 1 bach bach    0 2014-04-01 10:02 bc.3
-rw-rw-r-- 1 bach bach    0 2014-04-01 10:12 bc.1
-rw-rw-r-- 1 bach bach    0 2014-04-01 10:12 bc.2
drwxrwxr-x 2 bach bach 4096 2014-04-01 10:12 .

I do not care about the case for which there is more than one appearance of the substring a in the name of a file. It's ok if it will replace only the first occurrence. If it makes it much easier, I'm also ok with assuming the substring appears at the beginning of the filename, but I can't assume it is of fixed length.

Answer 1

This find (GNU) should work:

find . -type f -newermt 2014-03-30 ! -newermt 2014-04-01 -exec bash -c 'f="$1"; n="bc.${f##*.}"; mv "$f" "$n"' - '{}' \; 

Answer 2

Here is another one using findand bash parameter expansion inside a loop:

$ ls
a.file1.txt  a.file2.txt  a.file3.txt  b.file4.txt
b.file5.txt  b.file6.txt  c.file7.txt  c.file8.txt  c.file9.txt

$ files=($(find . -type f -newermt 2014-04-01 ! -newermt 2014-04-02))
$ for file in "${files[@]}"; do
> [[ "$file" =~ a. ]] && mv "$file" "${file/a./bc.}"
> done
$

$ ls
b.file4.txt  b.file5.txt  b.file6.txt  bc.file1.txt
bc.file2.txt  bc.file3.txt  c.file7.txt  c.file8.txt  c.file9.txt