mv command doesn't support renaming file (adding an index/number) when file already exists, so I created move.
move doesn't have any dependencies.
npm i -g @gauravnumber/move
move <source_path> <destination_path>
Initial Folder Structure
.
├── 1.txt
├── 2.txt
├── 3.txt
├── 4.txt
├── 5.txt
└── 6.txt
Execute the command below
move 1.txt 2.txt
2.txt file already exists, so move appends an index to the filename. After running above command, the folder structure looks like this.
.
├── 2_1.txt
├── 2.txt
├── 3.txt
├── 4.txt
├── 5.txt
└── 6.txt