cp - How to get duplicate files numbered as file1.txt_1, file1.txt_2, file.txt_3 when copying in BASH? -

in script, need copy files several directories, 1 directory, e.g.:

$ dir dir1    dir2    dir3    output $ cp */* output/ 

sometimes, there files same name though:

$ ls dir1/* file1.txt $ ls dir2/* file1.txt $ ls dir3/* file1.txt 

how can copy of files different directories, single directory, without filenames changed whenever 2 files identical names placed in same directory? sample result:

$ cp */* output/ $ ls output/ file1.txt_1 file1.txt_2 file1.txt_3 

a pretty simple way use --backup flag cp. files replaced rather leaving them, might sufficient. approach simple enough easy wrap alias around.

source ├── dir1 │   └── file1.txt ├── dir2 │   └── file2.txt ├── dir3 │   └── file1.txt └── dir4     └── file10.txt 

cp --backup=numbered source/dir*/* dest 

$ tree dest dest ├── file1.txt ├── file1.txt.~1~ ├── file10.txt └── file2.txt