这应该行得通：

#!/usr/bin/env sh

# Fail on error
set -o errexit
# Enable wildcard character expansion
set +o noglob

# ================
# CONFIGURATION
# ================
# PID directory
PID_DIR="status"
# Sleep time in seconds
SLEEP_TIME=1

# ================
# LOGGER
# ================
# Fatal log message
fatal() {
  printf '[FATAL] %s\n' "$@" >&2
  exit 1
}

# Warning log message
warn() {
  printf '[WARN ] %s\n' "$@" >&2
}

# Info log message
info() {
  printf '[INFO ] %s\n' "$@"
}

# ================
# MAIN
# ================
{
  # Check command 'ps' exists
  command -v ps > /dev/null 2>&1 || fatal "Command 'ps' not found"
  # Check command 'sleep' exists
  command -v sleep > /dev/null 2>&1 || fatal "Command 'sleep' not found"

  # Iterate files
  for _file in "$PID_DIR"/*; do
    # Skip if not file
    [ -f "$_file" ] || continue

    info "Analyzing file '$_file'"

    # Iterate PID
    while IFS='' read -r _pid; do
      info "Analyzing PID '$_pid'"

      # Wait PID
      while true; do
        info "Checking PID '$_pid'"

        # Check PID
        if ps -p "$_pid" > /dev/null 2>&1; then
          # PID exists
          warn "PID '$_pid' not terminated. Sleeping '$SLEEP_TIME' seconds..."
          sleep "$SLEEP_TIME"
        else
          # PID not exists
          info "PID '$_pid' terminated"
          break
        fi
      done
    done < "$_file"
  done

  # PIDs terminated
  info "All PIDs terminated"

  # ...
}

备注

因为wait仅在脚本是PID的父脚本时才起作用，所以必须不断地使用ps轮询它是否存在。