Learn spam in serial

spampipe.sh

#!/bin/bash

# Exit if *any* error is encountered
set -e

lockfile="/tmp/.sa-learn-lock"

# Make sure the lockfile exists
touch $lockfile
(
  # Get the name of the lockfile's descriptor
  unset descriptior
  exec {descriptor}< $lockfile
  
  # Block until you get an exclusive lock on that descriptor
  flock -e $descriptor
  
  cat | sa-learn "$@" &
  exit 0
)