Bash logger

bash-logger.sh

#!/bin/bash

# Logging level
: "${LOG_LEVEL:=INFO}"

# Associative arrays for logging
declare -A log_c log_l
# Color codes
log_c[0]='\033[0m'            # Reset colors
log_c[error]='\033[1;31m'     # Red
log_c[warning]='\033[1;33m'   # Yellow
log_c[info]='\033[1;34m'      # Blue
log_c[success]='\033[1;32m'   # Green
log_c[debug]='\033[1;37m'     # Gray
log_c[none]=''                # Nothing
# Logging priorities
log_l[silent]=0               # Higest prority, suppress all
log_l[error]=1
log_l[warning]=2
log_l[info]=3
log_l[success]=3
log_l[debug]=4                # Lowest prority, print all

# Print UTC date with format like: [05/17/21 20:05:21 UTC]
date-fmt() { date '+%D %T %Z' -u; }

log() {
  local lvl="${1:-debug}" color="${1:-debug}" msg="${*:2}" accent=debug ident=7

  # Check log level argument is valid, or set to debug
  [[ " ${!log_l[*]} " =~ \ "${lvl,,}"\  ]] || lvl=debug

  # Check interactive tty
  ! [ -t 1 ] && color=none && accent=none && ident=1

  # Redirect all messages to the third stream
  exec 3>&1
  # Redirect errors to stderr
  [ "${lvl,,}" == error ] && exec 3>&2
  # If the log level is >= to the msg level then not suppress messages
  [ "${log_l[${LOG_LEVEL,,}]}" -ge "${log_l[${lvl,,}]}" ] || exec 3>/dev/null

  # Print log message
  >&3 printf \
    "${log_c[${color,,}]}%-${ident}s${log_c[$accent]} [%s] ${log_c[0]}%s\n" \
    "${lvl^^}" "$(date-fmt)" "$msg"

  # Exiting the script when an error or success message appears
  [ "${lvl,,}" == error ] && exit 1
  [ "${lvl,,}" == success ] && exit 0
}

# Test
LOG_LEVEL=debug
for l in foo debug info warning success error; do
  log $l 'Voluptate sunt in dolor laboris ea amet eiusmod ad est quis labore.'
done