I corrected some typos. This one is syntactically correct:

     $ mv file.txt{,.bak}
     file.txt.bak
     $ mv file.txt.{bak,img}
     file.txt.img
     $ mv file.txt{.img,}
     file.txt

-Ramon

On 06/10/2022 17:19, Ramon Fischer wrote:
> And if you like Bash brace expansions; this one is sometimes quicker, 
> than tab-completion and removing characters:
>
>     $ mv file.txt{,.bak}
>     file.txt.bak
>     $ mv file.txt,{bak,img}
>     file.txt.img
>     $ mv file.txt{img,}
>     file.txt
>
> -Ramon 

-- 
GPG public key: 5983 98DA 5F4D A464 38FD CF87 155B E264 13E6 99BF