log.sh

# function to prefix each log output
#  over-ride to add custom output or format
#
# by default prints the script name ($0)
log_prefix() {
  echo "$0"
}

# default priority
_shlib_logp=6

# set the log priority
#  todo: fancy turn string into number
log_set_priority() {
  _shlib_logp="$1"
}

# if no args, return the priority
# if arg, then test if greater than or equals to priority
log_priority() {
  if test -z "${1-}"; then
    echo "$_shlib_logp"
    return
  fi
  [ "$1" -le "$_shlib_logp" ]
}

# log_tag: map a syslog priority number to its name
#
# Unrecognised values are echoed back unchanged.
log_tag() {
  case $1 in
    0) echo "emerg" ;;
    1) echo "alert" ;;
    2) echo "crit" ;;
    3) echo "err" ;;
    4) echo "warning" ;;
    5) echo "notice" ;;
    6) echo "info" ;;
    7) echo "debug" ;;
    *) echo "$1" ;;
  esac
}

# log_debug: log at debug priority (7)
log_debug() {
  log_priority 7 || return 0
  echoerr "$(log_prefix)" "$(log_tag 7)" "$@"
}

# log_info: log at info priority (6)
log_info() {
  log_priority 6 || return 0
  echoerr "$(log_prefix)" "$(log_tag 6)" "$@"
}

# log_err: log at error priority (3)
log_err() {
  log_priority 3 || return 0
  echoerr "$(log_prefix)" "$(log_tag 3)" "$@"
}

# log_crit: log at critical priority (2), for platform problems
log_crit() {
  log_priority 2 || return 0
  echoerr "$(log_prefix)" "$(log_tag 2)" "$@"
}