The -b option is used to define a directory in which TV will create a
backup-file TVback_<id>, in which <id> differs per platform. Under AmigaDOS,
it is the process number of the TV-session, under Unix, a random character
string. If no file name is specified, no backup-file will be created.
Note, that if TV is called without a -b option, it will create a
backup-file in the directory to which TVback is assigned (e.g. by
putting

     Assign TVback: <directory>

in the file s:User-Startup on Amiga).

The resulting backup-file can later be used as a command-file.

If the backup-file cnnot be opened, an error is generated.