How to convert audio file from .AU format to .MP3 format?

If you have FFmpeg installed, you can use the "ffmpeg" command to convert an audio file from .AU format to .MP3 format: "ffmpeg -i test.au -map 0:0 test.mp3". Here is an example of how to use the "ffmpeg" command:

\fyicener>ffmpeg -i test.au -map 0:0 test.mp3

ffmpeg version N-63378-g1d36def Copyright (c) 2000-2014 the FFmpeg 
  developers built on May 22 2014 22:01:44 with gcc 4.8.2 (GCC)
...
Guessed Channel Layout for  Input Stream #0.0 : mono
Input #0, au, from 'test.au':
  Duration: 00:05:53.14, start: 0.000000, bitrate: 64 kb/s
    Stream #0:0: Audio: pcm_mulaw ([1][0][0][0] / 0x0001), 8000 Hz, mono, s16, 6
4 kb/s
Output #0, mp3, to 'test.mp3':
  Metadata:
    TSSE            : Lavf55.40.100
    Stream #0:0: Audio: mp3 (libmp3lame), 8000 Hz, mono, s16p
    Metadata:
      encoder         : Lavc55.63.100 libmp3lame
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_mulaw -> libmp3lame)
Press [q] to stop, [?] for help
size=     345kB time=00:05:53.16 bitrate=   8.0kbits/s
video:0kB audio:345kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.073874%