Batch renaming files in MAC OSX - bash

Question

I have several thousand files with name like this:
PIN_PMN_PT_010_02_00331_0004_018edf
and need to rename them all something like this:
PIN_PMN_PT_010_02_00331_0004_018.edf
I have used simple mv scripts like this:
for f in *; do echo mv "$f" "`echo $f | tr 'edf' '.edf'`"; done
For some reason it creates names like this:
PIN_PMN_PT_010_02_00331_0004_018.ed
They are missing the last f. I am running the script using echo to dry run. Any ideas please?
Using MACBook Pro running Mohave 10.14.6 and Bash.

Answer 1

Use shell Parameter Expansion!
Simply under any shell:
For the test, echo to show what's will go:
for file in *edf ;do echo mv "$file" "${file%edf}.edf" ;done
Then, for doing the job:
for file in *edf ;do mv "$file" "${file%edf}.edf" ;done
(This must work same on MacOs, than under Linux.)
... And to prevent renaming of already correctly named files:
for file in *edf ;do test -f "${file##*.edf}" && mv "$file" "${file%edf}.edf" ;done
Syntax ${file##*.edf} will replace any string, terminated by .edf, by an empty string. So test -f "" will fail.
... Still: I don't have any Mac for doing the test, but as this is POSIX Standard, this must work on any shell. (Let my know, please comment!)
More infos?
Have a look at man sh or man bash and search for Parameter Expansion
man -P"less +'/Parameter Expansion'" bash

Answer 2

Using sed, this should work
for f in *; do echo mv "$f" "`echo $f | sed 's/.\{3\}$//`.edf"; done
You are just removing the last 3 characters of a string, and adding your file extension.

Answer 3

Personally, I find the rename command invaluable for this sort of thing:
rename 's/edf$/.edf/' *edf
If you want to do a dry-run, you can do:
rename --dry-run 's/edf$/.edf/' *edf
Sample Output
'PIN_PMN_PT_010_02_00331_0004_018edf' would be renamed to 'PIN_PMN_PT_010_02_00331_0004_018.edf'
The benefits of using rename are:
it can do a dry-run to test before you run for real
it will create all necessary directories with the -p option
it will not clobber (overwrite) files without warning
you have the full power of Perl available to you and can make your renaming as sophisticated as you wish.
As helpfully suggested by F. Hauri in the comments, you may have some files that have already had the dot inserted before the extension in your directory. To protect against insertion of a second dot, you could either be more specific in the files you select for renaming and only rename those ending in a digit followed by edf:
rename 's/edf$/.edf/' *[0-9]edf
Or, as F.Hauri suggested:
rename 's/([^.])edf$/$1.edf/' *edf
Note that you can install on macOS with homebrew:
brew install rename