Fixing mac os yosemite issue "bash: fork: Resource temporarily unavailable"

fixup.txt

# see the current limits
$ sysctl -a | grep maxproc

# increase it
$ sudo sysctl -w kern.maxproc=xxxx
$ sudo sysctl -w kern.maxprocperuid=xxx

# run at startup
$ sudo vim /etc/sysctl.conf

kern.maxproc=xxxx
kern.maxprocperuid=xxxx

$ sudo launchctl limit
$ sudo launchctl limit maxproc <maxprocperuid> <maxproc>
$ sudo launchctl limit maxfiles 512 unlimited

# run at startup
$ sudo vim /etc/launchd.conf

limit maxproc <maxprocperuid> <maxproc>
limit maxfiles 512 unlimited

A limit of 1064 processes on a 16 GB 8-core i7 Macbook is extremely low - I couldn't believe it when I first hit this "Cannot fork" issue.

from man 8 sysctl:

 The -w option has been deprecated and is silently ignored.

I also needed sudo sysctl kern.tty.ptmx_max=255 (or 511, or whatever). My default (in El Capitan) was 127. (As a tmux user, I need more than that.)