# logging faciality module for dracut both at build- and boot-time
# Copyright 2010 Amadeusz Żołnowski <aidecoe@aidecoe.name>
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
## @brief Logging facility module for dracut both at build- and boot-time.
# @section intro Introduction
# The logger takes a bit from Log4j philosophy. There are defined 6 logging
# The TRACE Level designates finer-grained informational events than the
# The DEBUG Level designates fine-grained informational events that are most
# useful to debug an application.
# The INFO level designates informational messages that highlight the
# progress of the application at coarse-grained level.
# The WARN level designates potentially harmful situations.
# The ERROR level designates error events that might still allow the
# application to continue running.
# The FATAL level designates very severe error events that will presumably
# lead the application to abort.
# Descriptions are borrowed from Log4j documentation:
# http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Level.html
# First of all you have to start with dlog_init() function which initializes
# required variables. Don't call any other logging function before that one!
# If you're ready with this, you can use following functions which corresponds
# clearly to levels listed in @ref intro Introduction. Here they are:
# They take all arguments given as a single message to be logged. See dlog()
# function for details how it works. Note that you shouldn't use dlog() by
# yourself. It's wrapped with above functions.
# @see dlog_init() dlog()
# @section conf Configuration
# Logging is controlled by following global variables:
# - @var stdloglvl - logging level to standard error (console output)
# - @var sysloglvl - logging level to syslog (by logger command)
# - @var fileloglvl - logging level to file
# - @var kmsgloglvl - logging level to /dev/kmsg (only for boot-time)
# - @var logfile - log file which is used when @var fileloglvl is higher
# and two global variables: @var maxloglvl and @var syslogfacility which <b>must
# not</b> be overwritten. Both are set by dlog_init(). @var maxloglvl holds
# maximum logging level of those three and indicates that dlog_init() was run.
# @var syslogfacility is set either to 'user' (when building initramfs) or
# 'daemon' (when booting).
# Logging level set by the variable means that messages from this logging level
# and above (FATAL is the highest) will be shown. Logging levels may be set
# independently for each destination (stderr, syslog, file, kmsg).
## @brief Initializes dracut Logger.
# @retval 1 if something has gone wrong
# @note This function need to be called before any other from this file.
# If any of the variables is not set, this function set it to default:
# - @var stdloglvl = 4 (info)
# - @var sysloglvl = 0 (no logging)
# - @var fileloglvl is set to 4 when @var logfile is set too, otherwise it's
# - @var kmsgloglvl = 0 (no logging)
# @warning Function sets global variables @var maxloglvl and @syslogfacility.
# See file doc comment for details.
local ret=0; local errmsg
[ -z "$stdloglvl" ] && stdloglvl=4
[ -z "$sysloglvl" ] && sysloglvl=0
[ -z "$kmsgloglvl" ] && kmsgloglvl=0
# Skip initialization if it's already done.
[ -n "$maxloglvl" ] && return 0
if [ -z "$fileloglvl" ]; then
[ -w "$logfile" ] && fileloglvl=4 || fileloglvl=0
elif (( $fileloglvl > 0 )); then
! [ -e "$logfile" ] && >"$logfile"
if [ -w "$logfile" -a -f "$logfile" ]; then
# Mark new run in the log file
if command -v date >/dev/null; then
echo "=== $(date) ===" >>"$logfile"
echo "===============================================" >>"$logfile"
# We cannot log to file, so turn this facility off.
errmsg="'$logfile' is not a writable file"
if (( $sysloglvl > 0 )); then
if [[ -d /run/systemd/journal ]] \
&& type -P systemd-cat &>/dev/null \
&& systemctl --quiet is-active systemd-journald.socket &>/dev/null \
&& { echo "dracut-$DRACUT_VERSION" | systemd-cat -t 'dracut' &>/dev/null; } ; then
readonly _systemdcatfile="$DRACUT_TMPDIR/systemd-cat"
mkfifo "$_systemdcatfile"
systemd-cat -t 'dracut' --level-prefix=true <"$_systemdcatfile" &
exec 15>"$_systemdcatfile"
elif ! [ -S /dev/log -a -w /dev/log ] || ! command -v logger >/dev/null; then
# We cannot log to syslog, so turn this facility off.
errmsg="No '/dev/log' or 'logger' included for syslog logging"
if (($sysloglvl > 0)) || (($kmsgloglvl > 0 )); then
if [ -n "$dracutbasedir" ]; then
readonly syslogfacility=user
readonly syslogfacility=daemon
local lvl; local maxloglvl_l=0
for lvl in $stdloglvl $sysloglvl $fileloglvl $kmsgloglvl; do
(( $lvl > $maxloglvl_l )) && maxloglvl_l=$lvl
readonly maxloglvl=$maxloglvl_l
if (($stdloglvl < 6)) && (($kmsgloglvl < 6)) && (($fileloglvl < 6)) && (($sysloglvl < 6)); then
if (($stdloglvl < 5)) && (($kmsgloglvl < 5)) && (($fileloglvl < 5)) && (($sysloglvl < 5)); then
if (($stdloglvl < 4)) && (($kmsgloglvl < 4)) && (($fileloglvl < 4)) && (($sysloglvl < 4)); then
if (($stdloglvl < 3)) && (($kmsgloglvl < 3)) && (($fileloglvl < 3)) && (($sysloglvl < 3)); then
if (($stdloglvl < 2)) && (($kmsgloglvl < 2)) && (($fileloglvl < 2)) && (($sysloglvl < 2)); then
if (($stdloglvl < 1)) && (($kmsgloglvl < 1)) && (($fileloglvl < 1)) && (($sysloglvl < 1)); then
[ -n "$errmsg" ] && derror "$errmsg"
## @brief Converts numeric logging level to the first letter of level name.
# @param lvl Numeric logging level in range from 1 to 6.
# @retval 1 if @a lvl is out of range.
# @retval 0 if @a lvl is correct.
# @result Echoes first letter of level name.
## @brief Converts numeric level to logger priority defined by POSIX.2.
# @param lvl Numeric logging level in range from 1 to 6.
# @retval 1 if @a lvl is out of range.
# @retval 0 if @a lvl is correct.
# @result Echoes logger priority.
## @brief Converts dracut-logger numeric level to syslog log level
# @param lvl Numeric logging level in range from 1 to 6.
# @retval 1 if @a lvl is out of range.
# @retval 0 if @a lvl is correct.
# @result Echoes kernel console numeric log level
# Conversion is done as follows:
# FATAL(1) -> LOG_CRIT (2)
# ERROR(2) -> LOG_ERR (3)
# WARN(3) -> LOG_WARNING (4)
# INFO(4) -> LOG_INFO (6)
# DEBUG(5) -> LOG_DEBUG (7)
# @see /usr/include/sys/syslog.h
[ "$syslogfacility" = user ] && echo $((8+$lvl)) || echo $((24+$lvl))
## @brief Prints to stderr and/or writes to file, to syslog and/or /dev/kmsg
# given message with given level (priority).
# @param lvl Numeric logging level.
# @retval 0 It's always returned, even if logging failed.
# @note This function is not supposed to be called manually. Please use
# dtrace(), ddebug(), or others instead which wrap this one.
# This is core logging function which logs given message to standard error, file
# and/or syslog (with POSIX shell command <tt>logger</tt>) and/or to /dev/kmsg.
# The format is following:
# <tt>X: some message</tt>
# where @c X is the first letter of logging level. See module description for
# Message to syslog is sent with tag @c dracut. Priorities are mapped as
# - @c WARN to @c warning
# - @c DEBUG and @c TRACE both to @c debug
local lvlc=$(_lvl2char "$lvl") || return 0
(( $lvl <= $stdloglvl )) && printf -- 'dracut: %s\n' "$msg" >&2
if (( $lvl <= $sysloglvl )); then
if [[ "$_dlogfd" ]]; then
printf -- "<%s>%s\n" "$(($(_dlvl2syslvl $lvl) & 7))" "$msg" >&$_dlogfd
logger -t "dracut[$$]" -p $(_lvl2syspri $lvl) -- "$msg"
if (( $lvl <= $fileloglvl )) && [[ -w "$logfile" ]] && [[ -f "$logfile" ]]; then
echo "$lmsg" >>"$logfile"
(( $lvl <= $kmsgloglvl )) && \
echo "<$(_dlvl2syslvl $lvl)>dracut[$$] $msg" >/dev/kmsg
## @brief Internal helper function for _do_dlog()
# @param lvl Numeric logging level.
# @retval 0 It's always returned, even if logging failed.
# @note This function is not supposed to be called manually. Please use
# dtrace(), ddebug(), or others instead which wrap this one.
# This function calls _do_dlog() either with parameter msg, or if
# none is given, it will read standard input and will use every line as
# dwarn "This is a warning"
# echo "This is a warning" | dwarn
[ -z "$maxloglvl" ] && return 0
(( $1 <= $maxloglvl )) || return 0
while read line || [ -n "$line" ]; do
## @brief Logs message at TRACE level (6)
# @retval 0 It's always returned, even if logging failed.
[ -n "$debug" ] && set -x || :
## @brief Logs message at DEBUG level (5)
# @retval 0 It's always returned, even if logging failed.
[ -n "$debug" ] && set -x || :
## @brief Logs message at INFO level (4)
# @retval 0 It's always returned, even if logging failed.
[ -n "$debug" ] && set -x || :
## @brief Logs message at WARN level (3)
# @retval 0 It's always returned, even if logging failed.
[ -n "$debug" ] && set -x || :
## @brief It's an alias to dwarn() function.
# @retval 0 It's always returned, even if logging failed.
[ -n "$debug" ] && set -x || :
## @brief Logs message at ERROR level (2)
# @retval 0 It's always returned, even if logging failed.
[ -n "$debug" ] && set -x || :
## @brief Logs message at FATAL level (1)
# @retval 0 It's always returned, even if logging failed.
[ -n "$debug" ] && set -x || :