Log4sh:Examples 1.4

From FeProductWiki

See also examples for 1.3

Examples and Workarounds for log4sh 1.4

Contents 1 Logging using two separate appenders

Logging using two separate appenders

Contributed by Laurent Georges.

The idea is to declare an appender in the log4sh.properties (called here HISTORY).

# Set root logger level to INFO and its only appender to A1 and HISTORY
log4sh.rootLogger = INFO, A1, HISTORY

At the beginning of your script, close the appender HISTORY, this way, no logs will be written in it.

# we close the HISTORY appender to avoid logging in it
appender_close HISTORY

Develop a little function which logs specifically in your appender with a given level:

history_info()
{
  # we reactivate the specific HISTORY appender
  appender_setLevel HISTORY INFO

  log_to_appender HISTORY INFO $1

  # we close the specific appender HISTORY
  appender_close HISTORY
}

The function above depends on extending log4sh, either by editing log4sh directly, or adding the function to the script where you need it.

#/**
# <s:function group="Logger" modifier="public">
# <entry align="right">
#   <emphasis>void</emphasis>
# </entry>
# <entry>
#   <funcsynopsis>
#     <funcprototype>
#       <funcdef><function>log_to_appender</function></funcdef>
#       <paramdef>string <parameter>appender name</parameter></paramdef>
#       <paramdef>string <parameter>level</parameter></paramdef>
#       <paramdef>string[] <parameter>message(s)</parameter></paramdef>
#     </funcprototype>
#   </funcsynopsis>
#   <para>This function logs a message to a specific appender </para>
#   <funcsynopsis>
#     <funcsynopsisinfo>log A1 DEBUG 'This is a test message'</funcsynopsisinfo>
#   </funcsynopsis>
# </entry>
# </s:function>
#*/
log_to_appender()
{
  _l_appenderName=$1
  shift
  _l_level=$1
  shift
  # if no message was passed, read it from STDIN
  [ $# -ne 0 ] && _l_msg="$@" || _l_msg=`cat`

  _l_levelInt=`logger_level_toInt ${_l_level}`

  # update seconds elapsed
  _log4sh_updateSeconds

  _l_oldIFS=${IFS} IFS=${__LOG4SH_IFS_DEFAULT}
  
    ${__LOG4SH_TRACE} "_l_appenderName='${_l_appenderName}'"
    # determine appender level
    _l_appenderLevel=`appender_getLevel ${_l_appenderName}`
    if [ "${_l_appenderLevel}" = "${__LOG4SH_NULL}" ]; then
      # continue if requested is level less than general level
      [ ! ${__log4shLevel} -le ${_l_levelInt} ] && DoNothing=1
    else
      _l_appenderLevelInt=`logger_level_toInt ${_l_appenderLevel}`
      # continue if requested level is less than specific appender level
      ${__LOG4SH_TRACE} "_l_levelInt='${_l_levelInt}' _l_appenderLevelInt='${_l_appenderLevelInt}'"
      [ ! ${_l_appenderLevelInt} -le ${_l_levelInt} ] && DoNothing=1
    fi

    # execute dynamic appender function
    if [[ $DoNothing != 1 ]]; then
        ${__LOG4SH_APPENDER_FUNC_PREFIX}${_l_appenderName}_append ${_l_level} "${_l_msg}"
    fi
  
  
  IFS=${_l_oldIFS}

  unset _l_msg _l_oldIFS _l_level _l_levelInt
  unset _l_appenderLevel _l_appenderLevelInt _l_appenderName DoNothing
}

This workaround has several drawbacks:

• You have to develop one function for each logging level you want to use (as we can not specify 2 different loggers in the properties file)
• It forces the log level (I did not find any other way as the CLOSE statement is in fact managed as a logging level)