Rename several gopro files - bash

Question

I have video files with this structure : GX**#### where #### is the number of the video.
But sometimes videos are splitted in 2 or 3 files, for instance : GX01#### and GX02####
My problem is that to organise my folders I prefer rename them like this : GX####-1 and GX####-2.
So i ask you the question if I can create a script/command to rename automatically my files to do this ? I can use .bat windows files or .sh linux files. My main problem is that i don't know a command to rename files simply (i saw many solutions which rewrite the entire file). May be if you know just this I will can do my script.
Thanks you in advance.

Answer 1

You can loop through the files and use PE parameter expansion to slice and jumble the strings and mv to rename the files.
Here is an example, first let us create an empty files using touch, but first we need to create a new directory (folder as you call it) and go into that newly created directory, using mkdir and cd.
mkdir newdirectory && cd newdirectory
Now create the empty files using touch.
touch GX01#### GX02#### GX03#### GX04####
Now check the empty files using ls
ls *
The output should be like
GX01#### GX02#### GX03#### GX04####
Now that we have created empty files, we can now do the renaming part.
for file in GX*; do
file1="${file#*??}"
file2=${file1#*??}
file3=${file1%*$file2}
echo mv -v "$file" "${file%*$file1}${file2}"-"$file3"
done
The output should be on stdout (which is your screen) because of the echo.
mv -v GX01#### GX####-01
mv -v GX02#### GX####-02
mv -v GX03#### GX####-03
mv -v GX04#### GX####-04
If you're satisfied with what you see then remove the echo, so mv can actually rename the files. To show how the slicing is done here is an example.
file=GX01####
file1="${file#*??}"
file2=${file1#*??}
file3="${file1%*$file2}"
printf '%s\n' "$file1" "$file2" "$file3"
The output should be something like.
01####
####
01
The ? means a single string from the shell.
A word of caution and advice, make a backup of the files you want to edit just in case the shell made a mistake while you're renaming the files. :-)
Also you should probably use shell globing like nullglob see
http://mywiki.wooledge.org/glob#nullglob
See man bash and look for Parameter Expansion.
PAGER='less +/^[[:space:]]*parameter\ expansion' man bash
Some online resources, with detailed explanation and examples.
http://mywiki.wooledge.org/BashFAQ/073
https://wiki.bash-hackers.org/syntax/pe

Answer 2

You could echo the original and new file names:
for f in GX*; do
echo "$f" $(sed 's/^GX\(..\)\(.*\)/GX\2-\1/' <<< "$f")
done
which should output:
GX01#### GX####-01
GX02#### GX####-02
then use mv -n instead of echo to rename the files.