GNU Parallel Bug Reports niceload: macos iostat differences

[PFudd]

Hello!

I just tried 'niceload' for the first time today, and I like what I see!

However, it turns out that Apple has a modified version of iostat, so 'niceload
-I 7 ........' gives this error:

==============
iostat: illegal option -- x
usage: iostat [-CUdIKoT?] [-c count] [-n devs]
              [-w wait] [drives]
Use of uninitialized value $io in division (/)
at /usr/local/bin/niceload line 659.
===============

The closest set of arguments for Macos I could find was:
===============
% iostat -d -c 2 -w 1
          disk0           disk1           disk2 
    KB/t tps  MB/s     KB/t tps  MB/s     KB/t tps  MB/s 
   20.19  32  0.63    10.65  57  0.59    23.64   1  0.02 
   74.47 197 14.35     4.00  27  0.11     0.00   0  0.00 
%
===============

As you can see, it does not give a '%util' field, the way linux does:
===============
Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz 
avgqu-sz   await r_await w_await  svctm  %util
sda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     
0.00    0.00    0.00    0.00   0.00   0.00
sdb               0.00     0.00    0.00    0.00     0.00     0.00
0.00     0.00    0.00    0.00    0.00   0.00   0.00
===============

This leaves us the unenviable task of estimating the highest throughput 
available for arbitrary devices: yuck!  Note: the MacOS Activity Monitor 
program has this problem too: the disk-io graph is rescaled constantly, just to 
keep the graph's maximum value in the last few minutes at about 80% of the y 
axis.

One other note: when I tried niceload -L on my linux virtual machine, I
found that I didn't even have iostat installed; I don't know whether
niceload should print a nicer error instead of 'sh: iostat: command not
found/division by zero error' or if the installation process should check for 
it; how do you feel?

Thanks for a great program!
--
PFudd  -- address@hidden