ulimit - a:

core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 31534
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 31534
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited


return from ffmpeg:

  amix -> Stream # 0: 0 (libmp3lame)
Press [q] to stop, [?] For help
Output # 0, mp3, to 'uploads / products / 18_01_2019_melodia.mp3':
  Metadata:
    TCON: Other
    TSSE: Lavf57.83.100
    Stream # 0: 0: Audio: mp3 (libmp3lame), 44100 Hz, stereo, fltp (default)
    Metadata:
      Encoder: Lavc57.107.100 libmp3lame
Killed 5888kB time = 00: 06: 26.56 bitrate = 124.8kbits / s speed = 6.7x