simple shell script logging utility - logging.sh

logging.sh

#!/bin/bash
# Prints all arguments passed to the function with a timestamp prepended. `LOG_DATE_STRING` can be
# overridden by exporting the var. Prepend to the log using `LOG_LEVEL`.
log() {
  [[ -z "$LOG_LEVEL" ]] && log_str='' || log_str="$LOG_LEVEL "
  log_str="${log_str}$(date "+${LOG_DATE_STRING-%Y-%m-%d %H:%M:%S}") $@"
  echo "$log_str"
}

info() { LOG_LEVEL='INFO' log "$@"; }
warn() { LOG_LEVEL='WARN' log "$@"; }
error() { LOG_LEVEL='ERROR' log "$@"; }

using-logging.sh

$ log my message
2016-06-06 16:08:44 my message
$ info my message
INFO 2016-06-06 16:08:44 my message
$ warn my message
WARN 2016-06-06 16:08:44 my message
$ error my message
ERROR 2016-06-06 16:08:44 my message
$ export LOG_DATE_STRING='+MY_DATE%H'
$ log my message
+MY_DATE16 my message
$ info my message
INFO +MY_DATE16 my message
$ warn my message
WARN +MY_DATE16 my message
$ error my message
ERROR +MY_DATE16 my message