Bash local variable gotcha

Bash local variables aren't as local as you'd like them to be:

function b() {
  local bvar
  echo "In b: '${avar}' '${bvar}'"
  avar=B  # modifies a's "local" variable
  bvar=B
}

function a() {
  local avar bvar
  avar=A
  bvar=A
  echo "In a before: '${avar}' '{$bvar}'"
  b
  echo "In a after:  '{$avar}' '{$bvar}'"
}

a

#---------------------- Prints --------------------------------

In a before: 'A' '{A}'

In b: 'A' ''

In a after:  '{B}' '{A}'