[ale] Pi - how to change /usr/local/bin when / is RO?

[neal at mnopltd.com]

I'm betting there is a way to do this.

JackTrip Virtual Studio runs on a Pi 3B.

Their init script needs to change to enable microphone bias voltage on 
startup.

amixer set 'ADC Mic Bias',0 'Mic Bias on'

In order for me to just hand this device to a musician and have them 
plug it in, I need to modify their init script in /usr/local/bin.

However, as you can see below, this is mounted read-only.

How does one get around this?

regards,

Neal


root at jacktrip:/usr/local/bin$ mount
/dev/mmcblk0p2 on / type ext4 (ro,noatime)
devtmpfs on /dev type devtmpfs 
(rw,relatime,size=440756k,nr_inodes=110189,mode=755)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
proc on /proc type proc (rw,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts 
(rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,nodev,mode=755)
tmpfs on /run/lock type tmpfs 
(rw,nosuid,nodev,noexec,relatime,size=5120k)
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755)
cgroup2 on /sys/fs/cgroup/unified type cgroup2 
(rw,nosuid,nodev,noexec,relatime,nsdelegate)
cgroup on /sys/fs/cgroup/systemd type cgroup 
(rw,nosuid,nodev,noexec,relatime,xattr,name=systemd)
none on /sys/fs/bpf type bpf (rw,nosuid,nodev,noexec,relatime,mode=700)
cgroup on /sys/fs/cgroup/blkio type cgroup 
(rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/pids type cgroup 
(rw,nosuid,nodev,noexec,relatime,pids)
cgroup on /sys/fs/cgroup/devices type cgroup 
(rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/net_cls type cgroup 
(rw,nosuid,nodev,noexec,relatime,net_cls)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup 
(rw,nosuid,nodev,noexec,relatime,cpu,cpuacct)
cgroup on /sys/fs/cgroup/freezer type cgroup 
(rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/cpuset type cgroup 
(rw,nosuid,nodev,noexec,relatime,cpuset)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs 
(rw,relatime,fd=29,pgrp=1,timeout=0,minproto=5,maxproto=5,direct)
mqueue on /dev/mqueue type mqueue (rw,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,relatime)
configfs on /sys/kernel/config type configfs (rw,relatime)
tmpfs on /var/tmp type tmpfs (rw,nosuid,nodev,relatime)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,relatime)
tmpfs on /var/log type tmpfs (rw,nosuid,nodev,relatime)
/dev/mmcblk0p1 on /boot type vfat 
(ro,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=ascii,shortname=mixed,errors=remount-ro)
tmpfs on /run/user/1000 type tmpfs 
(rw,nosuid,nodev,relatime,size=94804k,mode=700,uid=1000,gid=1000)