I want to create symlinks to all files in 'myfiles' which are not already linked to and specify the destination folder for the just-created symlinks.
I am using the following cmd, successfully, to generate the list of existing links, which point to 'myfolder' :
find ~/my-existing-links/ -lname '*/myfiles/*' -printf "%f\n" > results.txt
And I'm using the following cmd to reverse match i.e. to list the files in myfiles which are not linked to:
ls ~/myfiles | grep -vf results.txt > results2.txt
So, results2.txt has a list of the files, each of which I now want to create a new symlink to.... in a folder called ~/newlinks .
I know it is possible to feed 'ln -s' a file list using the find / exec combination i.e.
find ~/myfiles/ -exec ln -s {} -t ~/newlinks \; -print
.... but that would be the unfiltered file list in myfiles. I want to use the filtered list.
Any ideas how I can do this? I'm going to be adding files to myfiles regularly and so will periodically visit the folder for the purpose of generating symlinks for all the new files so I can divi the links up logically(rather than change the original filename).
Try with xargs:
cat results2.txt | xargs -I{} ln -s {} ~/newlinks
You can use xargs to apply the links, so that your composite command might look like this:
find ~/myfiles/ | grep -vf results.txt | xargs make-my-links
and make-my-links would be a script something like this:
#!/bin/sh
for source in "$#"
do
ln -s "$source" -t ~/newlinks
done
The separate script and loop are used with xargs because it does not accept a command-template, but will (default) send as many of the inputs as it thinks will fit on a command-line.
So, you have 3 entities of type directory:
~/myfiles/: contains your files.
~/my-existing-links/: contains links to files from ~/myfiles/.
~/newlinks/: contains links to new files from ~/myfiles/
To me, the third entity is rather unnecessary. Why the new links aren't created directly in ~/my-existing-links/?
I would only use a script to update the list of links in ~/my-existing-links/, whenever new files are added in ~/myfiles/:
update_v1.sh
#!/bin/bash
for f in $(find ~/myfiles -type f); do
ln -sf "$f" "~/my-existing-links/$(basename $f)"
done
update_v2.sh
find ~/myfiles -type f -exec sh -c \
'for f; do ln -sf "$f" "~/my-existing-links/${f#*/}"; done' sh {} +
update_print.sh
#!/bin/bash
for f in $(find ~/myfiles -type f); do
if [[ ! -L "~/my-existing-links/${f#*/}" ]]; then
echo "Link not existing for $f"
fi
done
Thanks, Thomas and pasaba... I found a way to do it:
So I did the following from ~/newlinks :
while read line; do ln -s "$line" "${line##*/}" ; done < ~/myfiles/results2.txt
Thanks again for your time.
I have a folder with more than 5000 images, all with JPG extension.
What i want to do, is to add recursively the "thumb_" prefix to all images.
I found a similar question: Rename Files and Directories (Add Prefix) but i only want to add the prefix to files with the JPG extension.
One of possibly solutions:
find . -name '*.jpg' -printf "'%p' '%h/thumb_%f'\n" | xargs -n2 echo mv
Principe: find all needed files, and prepare arguments for the standard mv command.
Notes:
arguments for the mv are surrounded by ' for allowing spaces in filenames.
The drawback is: this will not works with filenames what are containing ' apostrophe itself, like many mp3 files. If you need moving more strange filenames check bellow.
the above command is for dry run (only shows the mv commands with args). For real work remove the echo pretending mv.
ANY filename renaming. In the shell you need a delimiter. The problem is, than the filename (stored in a shell variable) usually can contain the delimiter itself, so:
mv $file $newfile #will fail, if the filename contains space, TAB or newline
mv "$file" "$newfile" #will fail, if the any of the filenames contains "
the correct solution are either:
prepare a filename with a proper escaping
use a scripting language what easuly understands ANY filename
Preparing the correct escaping in bash is possible with it's internal printf and %q formatting directive = print quoted. But this solution is long and boring.
IMHO, the easiest way is using perl and zero padded print0, like next.
find . -name \*.jpg -print0 | perl -MFile::Basename -0nle 'rename $_, dirname($_)."/thumb_".basename($_)'
The above using perl's power to mungle the filenames and finally renames the files.
Beware of filenames with spaces in (the for ... in ... expression trips over those), and be aware that the result of a find . ... will always start with ./ (and hence try to give you names like thumb_./file.JPG which isn't quite correct).
This is therefore not a trivial thing to get right under all circumstances. The expression I've found to work correctly (with spaces, subdirs and all that) is:
find . -iname \*.JPG -exec bash -c 'mv "$1" "`echo $1 | sed \"s/\(.*\)\//\1\/thumb/\"`"' -- '{}' \;
Even that can fall foul of certain names (with quotes in) ...
In OS X 10.8.5, find does not have the -printf option. The port that contained rename seemed to depend upon a WebkitGTK development package that was taking hours to install.
This one line, recursive file rename script worked for me:
find . -iname "*.jpg" -print | while read name; do cur_dir=$(dirname "$name"); cur_file=$(basename "$name"); mv "$name" "$cur_dir/thumb_$cur_file"; done
I was actually renaming CakePHP view files with an 'admin_' prefix, to move them all to an admin section.
You can use that same answer, just use *.jpg, instead of just *.
for file in *.JPG; do mv $file thumb_$file; done
if it's multiple directory levels under the current one:
for file in $(find . -name '*.JPG'); do mv $file $(dirname $file)/thumb_$(basename $file); done
proof:
jcomeau#intrepid:/tmp$ mkdir test test/a test/a/b test/a/b/c
jcomeau#intrepid:/tmp$ touch test/a/A.JPG test/a/b/B.JPG test/a/b/c/C.JPG
jcomeau#intrepid:/tmp$ cd test
jcomeau#intrepid:/tmp/test$ for file in $(find . -name '*.JPG'); do mv $file $(dirname $file)/thumb_$(basename $file); done
jcomeau#intrepid:/tmp/test$ find .
.
./a
./a/b
./a/b/thumb_B.JPG
./a/b/c
./a/b/c/thumb_C.JPG
./a/thumb_A.JPG
jcomeau#intrepid:/tmp/test$
Use rename for this:
rename 's/(\w{1})\.JPG$/thumb_$1\.JPG/' `find . -type f -name *.JPG`
For only jpg files in current folder
for f in `ls *.jpg` ; do mv "$f" "PRE_$f" ; done
Is it possible to copy a single file to multiple directories using the cp command ?
I tried the following , which did not work:
cp file1 /foo/ /bar/
cp file1 {/foo/,/bar}
I know it's possible using a for loop, or find. But is it possible using the gnu cp command?
You can't do this with cp alone but you can combine cp with xargs:
echo dir1 dir2 dir3 | xargs -n 1 cp file1
Will copy file1 to dir1, dir2, and dir3. xargs will call cp 3 times to do this, see the man page for xargs for details.
No, cp can copy multiple sources but will only copy to a single destination. You need to arrange to invoke cp multiple times - once per destination - for what you want to do; using, as you say, a loop or some other tool.
Wildcards also work with Roberts code
echo ./fs*/* | xargs -n 1 cp test
I would use cat and tee based on the answers I saw at https://superuser.com/questions/32630/parallel-file-copy-from-single-source-to-multiple-targets instead of cp.
For example:
cat inputfile | tee outfile1 outfile2 > /dev/null
As far as I can see it you can use the following:
ls | xargs -n 1 cp -i file.dat
The -i option of cp command means that you will be asked whether to overwrite a file in the current directory with the file.dat. Though it is not a completely automatic solution it worked out for me.
These answers all seem more complicated than the obvious:
for i in /foo /bar; do cp "$file1" "$i"; done
ls -db di*/subdir | xargs -n 1 cp File
-b in case there is a space in directory name otherwise it will be broken as a different item by xargs, had this problem with the echo version
Not using cp per se, but...
This came up for me in the context of copying lots of Gopro footage off of a (slow) SD card to three (slow) USB drives. I wanted to read the data only once, because it took forever. And I wanted it recursive.
$ tar cf - src | tee >( cd dest1 ; tar xf - ) >( cd dest2 ; tar xf - ) | ( cd dest3 ; tar xf - )
(And you can add more of those >() sections if you want more outputs.)
I haven't benchmarked that, but it's definitely a lot faster than cp-in-a-loop (or a bunch of parallel cp invocations).
If you want to do it without a forked command:
tee <inputfile file2 file3 file4 ... >/dev/null
To use copying with xargs to directories using wildcards on Mac OS, the only solution that worked for me with spaces in the directory name is:
find ./fs*/* -type d -print0 | xargs -0 -n 1 cp test
Where test is the file to copy
And ./fs*/* the directories to copy to
The problem is that xargs sees spaces as a new argument, the solutions to change the delimiter character using -d or -E is unfortunately not properly working on Mac OS.
Essentially equivalent to the xargs answer, but in case you want parallel execution:
parallel -q cp file1 ::: /foo/ /bar/
So, for example, to copy file1 into all subdirectories of current folder (including recursion):
parallel -q cp file1 ::: `find -mindepth 1 -type d`
N.B.: This probably only conveys any noticeable speed gains for very specific use cases, e.g. if each target directory is a distinct disk.
It is also functionally similar to the '-P' argument for xargs.
No - you cannot.
I've found on multiple occasions that I could use this functionality so I've made my own tool to do this for me.
http://github.com/ddavison/branch
pretty simple -
branch myfile dir1 dir2 dir3
ls -d */ | xargs -iA cp file.txt A
Suppose you want to copy fileName.txt to all sub-directories within present working directory.
Get all sub-directories names through ls and save them to some temporary file say, allFolders.txt
ls > allFolders.txt
Print the list and pass it to command xargs.
cat allFolders.txt | xargs -n 1 cp fileName.txt
Another way is to use cat and tee as follows:
cat <source file> | tee <destination file 1> | tee <destination file 2> [...] > <last destination file>
I think this would be pretty inefficient though, since the job would be split among several processes (one per destination) and the hard drive would be writing several files at once over different parts of the platter. However if you wanted to write a file out to several different drives, this method would probably be pretty efficient (as all copies could happen concurrently).
Using a bash script
DESTINATIONPATH[0]="xxx/yyy"
DESTINATIONPATH[1]="aaa/bbb"
..
DESTINATIONPATH[5]="MainLine/USER"
NumberOfDestinations=6
for (( i=0; i<NumberOfDestinations; i++))
do
cp SourcePath/fileName.ext ${DESTINATIONPATH[$i]}
done
exit
if you want to copy multiple folders to multiple folders one can do something like this:
echo dir1 dir2 dir3 | xargs -n 1 cp -r /path/toyourdir/{subdir1,subdir2,subdir3}
If all your target directories match a path expression — like they're all subdirectories of path/to — then just use find in combination with cp like this:
find ./path/to/* -type d -exec cp [file name] {} \;
That's it.
If you need to be specific on into which folders to copy the file you can combine find with one or more greps. For example to replace any occurences of favicon.ico in any subfolder you can use:
find . | grep favicon\.ico | xargs -n 1 cp -f /root/favicon.ico
This will copy to the immediate sub-directories, if you want to go deeper, adjust the -maxdepth parameter.
find . -mindepth 1 -maxdepth 1 -type d| xargs -n 1 cp -i index.html
If you don't want to copy to all directories, hopefully you can filter the directories you are not interested in. Example copying to all folders starting with a
find . -mindepth 1 -maxdepth 1 -type d| grep \/a |xargs -n 1 cp -i index.html
If copying to a arbitrary/disjoint set of directories you'll need Robert Gamble's suggestion.
I like to copy a file into multiple directories as such:
cp file1 /foo/; cp file1 /bar/; cp file1 /foo2/; cp file1 /bar2/
And copying a directory into other directories:
cp -r dir1/ /foo/; cp -r dir1/ /bar/; cp -r dir1/ /foo2/; cp -r dir1/ /bar2/
I know it's like issuing several commands, but it works well for me when I want to type 1 line and walk away for a while.
For example if you are in the parent directory of you destination folders you can do:
for i in $(ls); do cp sourcefile $i; done
I have to rename a complete folder tree recursively so that no uppercase letter appears anywhere (it's C++ source code, but that shouldn't matter).
Bonus points for ignoring CVS and Subversion version control files/folders. The preferred way would be a shell script, since a shell should be available on any Linux box.
There were some valid arguments about details of the file renaming.
I think files with the same lowercase names should be overwritten; it's the user's problem. When checked out on a case-ignoring file system, it would overwrite the first one with the latter, too.
I would consider A-Z characters and transform them to a-z, everything else is just calling for problems (at least with source code).
The script would be needed to run a build on a Linux system, so I think changes to CVS or Subversion version control files should be omitted. After all, it's just a scratch checkout. Maybe an "export" is more appropriate.
Smaller still I quite like:
rename 'y/A-Z/a-z/' *
On case insensitive filesystems such as OS X's HFS+, you will want to add the -f flag:
rename -f 'y/A-Z/a-z/' *
A concise version using the "rename" command:
find my_root_dir -depth -exec rename 's/(.*)\/([^\/]*)/$1\/\L$2/' {} \;
This avoids problems with directories being renamed before files and trying to move files into non-existing directories (e.g. "A/A" into "a/a").
Or, a more verbose version without using "rename".
for SRC in `find my_root_dir -depth`
do
DST=`dirname "${SRC}"`/`basename "${SRC}" | tr '[A-Z]' '[a-z]'`
if [ "${SRC}" != "${DST}" ]
then
[ ! -e "${DST}" ] && mv -T "${SRC}" "${DST}" || echo "${SRC} was not renamed"
fi
done
P.S.
The latter allows more flexibility with the move command (for example, "svn mv").
for f in `find`; do mv -v "$f" "`echo $f | tr '[A-Z]' '[a-z]'`"; done
Just simply try the following if you don't need to care about efficiency.
zip -r foo.zip foo/*
unzip -LL foo.zip
One can simply use the following which is less complicated:
rename 'y/A-Z/a-z/' *
This works on CentOS/Red Hat Linux or other distributions without the rename Perl script:
for i in $( ls | grep [A-Z] ); do mv -i "$i" "`echo $i | tr 'A-Z' 'a-z'`"; done
Source: Rename all file names from uppercase to lowercase characters
(In some distributions the default rename command comes from util-linux, and that is a different, incompatible tool.)
This works if you already have or set up the rename command (e.g. through brew install in Mac):
rename --lower-case --force somedir/*
The simplest approach I found on Mac OS X was to use the rename package from http://plasmasturm.org/code/rename/:
brew install rename
rename --force --lower-case --nows *
--force Rename even when a file with the destination name already exists.
--lower-case Convert file names to all lower case.
--nows Replace all sequences of whitespace in the filename with single underscore characters.
Most of the answers above are dangerous, because they do not deal with names containing odd characters. Your safest bet for this kind of thing is to use find's -print0 option, which will terminate filenames with ASCII NUL instead of \n.
Here is a script, which only alter files and not directory names so as not to confuse find:
find . -type f -print0 | xargs -0n 1 bash -c \
's=$(dirname "$0")/$(basename "$0");
d=$(dirname "$0")/$(basename "$0"|tr "[A-Z]" "[a-z]"); mv -f "$s" "$d"'
I tested it, and it works with filenames containing spaces, all kinds of quotes, etc. This is important because if you run, as root, one of those other scripts on a tree that includes the file created by
touch \;\ echo\ hacker::0:0:hacker:\$\'\057\'root:\$\'\057\'bin\$\'\057\'bash
... well guess what ...
Here's my suboptimal solution, using a Bash shell script:
#!/bin/bash
# First, rename all folders
for f in `find . -depth ! -name CVS -type d`; do
g=`dirname "$f"`/`basename "$f" | tr '[A-Z]' '[a-z]'`
if [ "xxx$f" != "xxx$g" ]; then
echo "Renaming folder $f"
mv -f "$f" "$g"
fi
done
# Now, rename all files
for f in `find . ! -type d`; do
g=`dirname "$f"`/`basename "$f" | tr '[A-Z]' '[a-z]'`
if [ "xxx$f" != "xxx$g" ]; then
echo "Renaming file $f"
mv -f "$f" "$g"
fi
done
Folders are all renamed correctly, and mv isn't asking questions when permissions don't match, and CVS folders are not renamed (CVS control files inside that folder are still renamed, unfortunately).
Since "find -depth" and "find | sort -r" both return the folder list in a usable order for renaming, I preferred using "-depth" for searching folders.
One-liner:
for F in K*; do NEWNAME=$(echo "$F" | tr '[:upper:]' '[:lower:]'); mv "$F" "$NEWNAME"; done
Or even:
for F in K*; do mv "$F" "${F,,}"; done
Note that this will convert only files/directories starting with letter K, so adjust accordingly.
The original question asked for ignoring SVN and CVS directories, which can be done by adding -prune to the find command. E.g to ignore CVS:
find . -name CVS -prune -o -exec mv '{}' `echo {} | tr '[A-Z]' '[a-z]'` \; -print
[edit] I tried this out, and embedding the lower-case translation inside the find didn't work for reasons I don't actually understand. So, amend this to:
$> cat > tolower
#!/bin/bash
mv $1 `echo $1 | tr '[:upper:]' '[:lower:]'`
^D
$> chmod u+x tolower
$> find . -name CVS -prune -o -exec tolower '{}' \;
Ian
Not portable, Zsh only, but pretty concise.
First, make sure zmv is loaded.
autoload -U zmv
Also, make sure extendedglob is on:
setopt extendedglob
Then use:
zmv '(**/)(*)~CVS~**/CVS' '${1}${(L)2}'
To recursively lowercase files and directories where the name is not CVS.
Using Larry Wall's filename fixer:
$op = shift or die $help;
chomp(#ARGV = <STDIN>) unless #ARGV;
for (#ARGV) {
$was = $_;
eval $op;
die $# if $#;
rename($was,$_) unless $was eq $_;
}
It's as simple as
find | fix 'tr/A-Z/a-z/'
(where fix is of course the script above)
for f in `find -depth`; do mv ${f} ${f,,} ; done
find -depth prints each file and directory, with a directory's contents printed before the directory itself. ${f,,} lowercases the file name.
This works nicely on macOS too:
ruby -e "Dir['*'].each { |p| File.rename(p, p.downcase) }"
This is a small shell script that does what you requested:
root_directory="${1?-please specify parent directory}"
do_it () {
awk '{ lc= tolower($0); if (lc != $0) print "mv \"" $0 "\" \"" lc "\"" }' | sh
}
# first the folders
find "$root_directory" -depth -type d | do_it
find "$root_directory" ! -type d | do_it
Note the -depth action in the first find.
Use typeset:
typeset -l new # Always lowercase
find $topPoint | # Not using xargs to make this more readable
while read old
do new="$old" # $new is a lowercase version of $old
mv "$old" "$new" # Quotes for those annoying embedded spaces
done
On Windows, emulations, like Git Bash, may fail because Windows isn't case-sensitive under the hood. For those, add a step that mv's the file to another name first, like "$old.tmp", and then to $new.
With MacOS,
Install the rename package,
brew install rename
Use,
find . -iname "*.py" -type f | xargs -I% rename -c -f "%"
This command find all the files with a *.py extension and converts the filenames to lower case.
`f` - forces a rename
For example,
$ find . -iname "*.py" -type f
./sample/Sample_File.py
./sample_file.py
$ find . -iname "*.py" -type f | xargs -I% rename -c -f "%"
$ find . -iname "*.py" -type f
./sample/sample_file.py
./sample_file.py
Lengthy But "Works With No Surprises & No Installations"
This script handles filenames with spaces, quotes, other unusual characters and Unicode, works on case insensitive filesystems and most Unix-y environments that have bash and awk installed (i.e. almost all). It also reports collisions if any (leaving the filename in uppercase) and of course renames both files & directories and works recursively. Finally it's highly adaptable: you can tweak the find command to target the files/dirs you wish and you can tweak awk to do other name manipulations. Note that by "handles Unicode" I mean that it will indeed convert their case (not ignore them like answers that use tr).
# adapt the following command _IF_ you want to deal with specific files/dirs
find . -depth -mindepth 1 -exec bash -c '
for file do
# adapt the awk command if you wish to rename to something other than lowercase
newname=$(dirname "$file")/$(basename "$file" | awk "{print tolower(\$0)}")
if [ "$file" != "$newname" ] ; then
# the extra step with the temp filename is for case-insensitive filesystems
if [ ! -e "$newname" ] && [ ! -e "$newname.lcrnm.tmp" ] ; then
mv -T "$file" "$newname.lcrnm.tmp" && mv -T "$newname.lcrnm.tmp" "$newname"
else
echo "ERROR: Name already exists: $newname"
fi
fi
done
' sh {} +
References
My script is based on these excellent answers:
https://unix.stackexchange.com/questions/9496/looping-through-files-with-spaces-in-the-names
How to convert a string to lower case in Bash?
In OS X, mv -f shows "same file" error, so I rename twice:
for i in `find . -name "*" -type f |grep -e "[A-Z]"`; do j=`echo $i | tr '[A-Z]' '[a-z]' | sed s/\-1$//`; mv $i $i-1; mv $i-1 $j; done
I needed to do this on a Cygwin setup on Windows 7 and found that I got syntax errors with the suggestions from above that I tried (though I may have missed a working option). However, this solution straight from Ubuntu forums worked out of the can :-)
ls | while read upName; do loName=`echo "${upName}" | tr '[:upper:]' '[:lower:]'`; mv "$upName" "$loName"; done
(NB: I had previously replaced whitespace with underscores using:
for f in *\ *; do mv "$f" "${f// /_}"; done
)
Slugify Rename (regex)
It is not exactly what the OP asked for, but what I was hoping to find on this page:
A "slugify" version for renaming files so they are similar to URLs (i.e. only include alphanumeric, dots, and dashes):
rename "s/[^a-zA-Z0-9\.]+/-/g" filename
I would reach for Python in this situation, to avoid optimistically assuming paths without spaces or slashes. I've also found that python2 tends to be installed in more places than rename.
#!/usr/bin/env python2
import sys, os
def rename_dir(directory):
print('DEBUG: rename('+directory+')')
# Rename current directory if needed
os.rename(directory, directory.lower())
directory = directory.lower()
# Rename children
for fn in os.listdir(directory):
path = os.path.join(directory, fn)
os.rename(path, path.lower())
path = path.lower()
# Rename children within, if this child is a directory
if os.path.isdir(path):
rename_dir(path)
# Run program, using the first argument passed to this Python script as the name of the folder
rename_dir(sys.argv[1])
If you use Arch Linux, you can install rename) package from AUR that provides the renamexm command as /usr/bin/renamexm executable and a manual page along with it.
It is a really powerful tool to quickly rename files and directories.
Convert to lowercase
rename -l Developers.mp3 # or --lowcase
Convert to UPPER case
rename -u developers.mp3 # or --upcase, long option
Other options
-R --recursive # directory and its children
-t --test # Dry run, output but don't rename
-o --owner # Change file owner as well to user specified
-v --verbose # Output what file is renamed and its new name
-s/str/str2 # Substitute string on pattern
--yes # Confirm all actions
You can fetch the sample Developers.mp3 file from here, if needed ;)
None of the solutions here worked for me because I was on a system that didn't have access to the perl rename script, plus some of the files included spaces. However, I found a variant that works:
find . -depth -exec sh -c '
t=${0%/*}/$(printf %s "${0##*/}" | tr "[:upper:]" "[:lower:]");
[ "$t" = "$0" ] || mv -i "$0" "$t"
' {} \;
Credit goes to "Gilles 'SO- stop being evil'", see this answer on the similar question "change entire directory tree to lower-case names" on the Unix & Linux StackExchange.
I believe the one-liners can be simplified:
for f in **/*; do mv "$f" "${f:l}"; done
( find YOURDIR -type d | sort -r;
find yourdir -type f ) |
grep -v /CVS | grep -v /SVN |
while read f; do mv -v $f `echo $f | tr '[A-Z]' '[a-z]'`; done
First rename the directories bottom up sort -r (where -depth is not available), then the files.
Then grep -v /CVS instead of find ...-prune because it's simpler.
For large directories, for f in ... can overflow some shell buffers.
Use find ... | while read to avoid that.
And yes, this will clobber files which differ only in case...
find . -depth -name '*[A-Z]*'|sed -n 's/\(.*\/\)\(.*\)/mv -n -v -T \1\2 \1\L\2/p'|sh
I haven't tried the more elaborate scripts mentioned here, but none of the single commandline versions worked for me on my Synology NAS. rename is not available, and many of the variations of find fail because it seems to stick to the older name of the already renamed path (eg, if it finds ./FOO followed by ./FOO/BAR, renaming ./FOO to ./foo will still continue to list ./FOO/BAR even though that path is no longer valid). Above command worked for me without any issues.
What follows is an explanation of each part of the command:
find . -depth -name '*[A-Z]*'
This will find any file from the current directory (change . to whatever directory you want to process), using a depth-first search (eg., it will list ./foo/bar before ./foo), but only for files that contain an uppercase character. The -name filter only applies to the base file name, not the full path. So this will list ./FOO/BAR but not ./FOO/bar. This is ok, as we don't want to rename ./FOO/bar. We want to rename ./FOO though, but that one is listed later on (this is why -depth is important).
This comand in itself is particularly useful to finding the files that you want to rename in the first place. Use this after the complete rename command to search for files that still haven't been replaced because of file name collisions or errors.
sed -n 's/\(.*\/\)\(.*\)/mv -n -v -T \1\2 \1\L\2/p'
This part reads the files outputted by find and formats them in a mv command using a regular expression. The -n option stops sed from printing the input, and the p command in the search-and-replace regex outputs the replaced text.
The regex itself consists of two captures: the part up until the last / (which is the directory of the file), and the filename itself. The directory is left intact, but the filename is transformed to lowercase. So, if find outputs ./FOO/BAR, it will become mv -n -v -T ./FOO/BAR ./FOO/bar. The -n option of mv makes sure existing lowercase files are not overwritten. The -v option makes mv output every change that it makes (or doesn't make - if ./FOO/bar already exists, it outputs something like ./FOO/BAR -> ./FOO/BAR, noting that no change has been made). The -T is very important here - it treats the target file as a directory. This will make sure that ./FOO/BAR isn't moved into ./FOO/bar if that directory happens to exist.
Use this together with find to generate a list of commands that will be executed (handy to verify what will be done without actually doing it)
sh
This pretty self-explanatory. It routes all the generated mv commands to the shell interpreter. You can replace it with bash or any shell of your liking.
Using bash, without rename:
find . -exec bash -c 'mv $0 ${0,,}' {} \;