Fix yet another sed bug. The s/// command would copy the \ of substitutions before deciding what to do with them (generally overwriting the \ with the new data). When the substitution was A) at the very end of the new string, B) resolved to nothing, it could leave a trailing \ that didn't belong there and didn't get overwritten because the "copy trailing data" part that copies the original string's null terminator already happened before the \ overwrote it. The ghostwheel() function restarts regexes after embedded NUL bytes, but if the string it's passed is _longer_ than the length it's told then it gets confused (and it means we're off the end of our allocation so segfaults are likely). Fix: test for \ first and move the "copy byte" logic into an else case.

#!/bin/bash

# If you want to use toybox netcat to talk to a serial port, use this.

if [ ! -c "$1" ]
then
  echo "Usage: minicom.sh /dev/ttyS0"
  exit 1
fi

SPEED="$2"
[ -z "$SPEED" ] && SPEED=115200

stty $SPEED -F "$1"
stty raw -echo -ctlecho -F "$1"
stty raw -echo  # Need to do it on stdin, too.
./toybox netcat -f "$1"
stty cooked echo  # Put stdin back.