bash-logger.sh

#!/bin/bash
#--------------------------------------------------------------------------------------------------
# Bash Logger
# Copyright (c) Dean Rather
# Licensed under the MIT license
# http://github.com/deanrather/bash-logger
#--------------------------------------------------------------------------------------------------

#--------------------------------------------------------------------------------------------------
# Configurables

export LOGFILE=~/bash-logger.log
export LOG_FORMAT='%DATE %PID [%LEVEL] %MESSAGE'
export LOG_DATE_FORMAT='+%F %T %Z'                  # Eg: 2014-09-07 21:51:57 EST
export LOG_COLOR_DEBUG="\033[0;37m"                 # Gray
export LOG_COLOR_INFO="\033[0m"                     # White
export LOG_COLOR_NOTICE="\033[1;32m"                # Green
export LOG_COLOR_WARNING="\033[1;33m"               # Yellow
export LOG_COLOR_ERROR="\033[1;31m"                 # Red
export LOG_COLOR_CRITICAL="\033[44m"                # Blue Background
export LOG_COLOR_ALERT="\033[43m"                   # Yellow Background
export LOG_COLOR_EMERGENCY="\033[41m"               # Red Background
export RESET_COLOR="\033[0m"

#--------------------------------------------------------------------------------------------------
# Individual Log Functions
# These can be overwritten to provide custom behavior for different log levels

DEBUG()     { LOG_HANDLER_DEFAULT "$FUNCNAME" "$@"; }
INFO()      { LOG_HANDLER_DEFAULT "$FUNCNAME" "$@"; }
NOTICE()    { LOG_HANDLER_DEFAULT "$FUNCNAME" "$@"; }
WARNING()   { LOG_HANDLER_DEFAULT "$FUNCNAME" "$@"; }
ERROR()     { LOG_HANDLER_DEFAULT "$FUNCNAME" "$@"; exit 1; }
CRITICAL()  { LOG_HANDLER_DEFAULT "$FUNCNAME" "$@"; exit 1; }
ALERT()     { LOG_HANDLER_DEFAULT "$FUNCNAME" "$@"; exit 1; }
EMERGENCY() { LOG_HANDLER_DEFAULT "$FUNCNAME" "$@"; exit 1; }

#--------------------------------------------------------------------------------------------------
# Helper Functions

# Outputs a log formatted using the LOG_FORMAT and DATE_FORMAT configurables
# Usage: FORMAT_LOG <log level> <log message>
# Eg: FORMAT_LOG CRITICAL "My critical log"
FORMAT_LOG() {
    local level="$1"
    local log="$2"
    local pid=$$
    local date="$(date "$LOG_DATE_FORMAT")"
    local formatted_log="$LOG_FORMAT"
    formatted_log="${formatted_log/'%MESSAGE'/$log}"
    formatted_log="${formatted_log/'%LEVEL'/$level}"
    formatted_log="${formatted_log/'%PID'/$pid}"
    formatted_log="${formatted_log/'%DATE'/$date}"
    echo "$formatted_log\n"
}

# Calls one of the individual log functions
# Usage: LOG <log level> <log message>
# Eg: LOG INFO "My info log"
LOG() {
    local level="$1"
    local log="$2"
    local log_function_name="${!level}"
    $log_function_name "$log"
}

#--------------------------------------------------------------------------------------------------
# Log Handlers

# All log levels call this handler (by default...), so this is a great place to put any standard
# logging behavior
# Usage: LOG_HANDLER_DEFAULT <log level> <log message>
# Eg: LOG_HANDLER_DEFAULT DEBUG "My debug log"
LOG_HANDLER_DEFAULT() {
    # $1 - level
    # $2 - message
    local formatted_log="$(FORMAT_LOG "$@")"
    LOG_HANDLER_COLORTERM "$1" "$formatted_log"
    LOG_HANDLER_LOGFILE "$1" "$formatted_log"
}

# Outputs a log to the stdout, colourised using the LOG_COLOR configurables
# Usage: LOG_HANDLER_COLORTERM <log level> <log message>
# Eg: LOG_HANDLER_COLORTERM CRITICAL "My critical log"
LOG_HANDLER_COLORTERM() {
    local level="$1"
    local log="$2"
    local color_variable="LOG_COLOR_$level"
    local color="${!color_variable}"
    log="$color$log$RESET_COLOR"
    echo -en "$log"
}

# Appends a log to the configured logfile
# Usage: LOG_HANDLER_LOGFILE <log level> <log message>
# Eg: LOG_HANDLER_LOGFILE NOTICE "My critical log"
LOG_HANDLER_LOGFILE() {
    local level="$1"
    local log="$2"
    local log_path="$(dirname "$LOGFILE")"
    [ -d "$log_path" ] || mkdir -p "$log_path"
    echo "$log" >> "$LOGFILE"
}