Use the `mv` command:
`mv old_filename new_filename`
Example: `mv file1.txt file2.txt`
To rename a file in another directory:
`mv /path/to/old_filename /path/to/new_filename`
If the file name contains spaces, use quotes:
`mv “old file.txt” “new file.txt”`
To rename multiple files, use a loop or a rename tool
Example with `rename`:
`rename ‘s/old/new/’ *.txt`