I have been trying to modify this log4bash implementation but I cannot manage to make it work. Here's a sample:

    #!/bin/bash

    TRUE=1
    FALSE=0

    ############### Added for testing
    log4bash_LOG_ENABLED=$TRUE

    log4bash_rootLogger=$TRACE,f,s
    log4bash_appender_f=file
    log4bash_appender_f_dir=$(pwd)
    log4bash_appender_f_file=test.log
    log4bash_appender_f_roll_format=%Y%m
    log4bash_appender_f_roll=$TRUE
    log4bash_appender_f_maxBackupIndex=10

    ####################################

    log4bash_abs(){
            if [ "${1:0:1}" == "." ]; then
                    builtin echo ${rootDir}/${1}
            else
                    builtin echo ${1}
            fi
    }

    log4bash_check_app_dir(){

    if [ "$log4bash_LOG_ENABLED" -eq $TRUE ]; then
      dir=$(log4bash_abs $1)
      if [ ! -d ${dir} ]; then
        #log a seperation line
        mkdir $dir
      fi
    fi
    }

    # Delete old log files
    # $1 Log directory
    # $2 Log filename
    # $3 Log filename suffix
    # $4 Max backup index
    log4bash_delete_old_files(){
    ##### Added for testing
    builtin echo "Running log4bash_delete_old_files $@" >&2
    #####
    if [ "$log4bash_LOG_ENABLED" -eq $TRUE ] && [ -n "$3" ] && [ "$4" -gt 0 ]; then
            local directory=$(log4bash_abs $1)
            local filename=$2
            local maxBackupIndex=$4
            local suffix=$(echo "${3}" | sed -re 's/[^.]/?/g')
            local logFileList=$(find "${directory}" -mindepth 1 -maxdepth 1 -name "${filename}${suffix}" -type f | xargs ls -1rt)
            local fileCnt=$(builtin echo -e "${logFileList}" | wc -l)
            local fileToDeleteCnt=$(($fileCnt-$maxBackupIndex))
            local fileToDelete=($(builtin echo -e "${logFileList}" | head -n "${fileToDeleteCnt}" | sed ':a;N;$!ba;s/\n/ /g'))

            ##### Added for testing
            builtin echo "log4bash_delete_old_files About to start deletion ${fileToDelete[@]}" >&2
            #####

            if [ ${fileToDeleteCnt} -gt 0 ]; then
                    for f in "${fileToDelete[@]}"; do
                            #### Added for testing
                            builtin echo "Removing file ${f}" >&2
                            ####
                            builtin eval rm -f ${f}
                    done
            fi
    fi
    }

    #Appender
    # $1 Log directory
    # $2 Log file
    # $3 Log file roll ?
    # $4 Appender Name
    log4bash_filename(){
    builtin echo "Running log4bash_filename $@" >&2
            local format
            local filename

            log4bash_check_app_dir "${1}"

            if [ ${3} -eq 1 ];then
                    local formatProp=${4}_roll_format
                    format=${!formatProp}
                    if [ -z ${format} ]; then
                            format=$log4bash_appender_file_format
                    fi
                    local suffix=.`date "+${format}"`

                    filename=${1}/${2}${suffix}

                    # Old log files deletion
                    local previousFilenameVar=int_${4}_file_previous
                    local maxBackupIndexVar=${4}_maxBackupIndex

                    if [ -n "${!maxBackupIndexVar}" ] && [ "${!previousFilenameVar}" != "${filename}" ]; then
                            builtin eval export $previousFilenameVar=$filename
                            log4bash_delete_old_files "${1}" "${2}" "${suffix}" "${!maxBackupIndexVar}"
                    else
                            builtin echo "log4bash_filename $previousFilenameVar => ${!previousFilenameVar}"
                    fi
            else
                    filename=${1}/${2}
            fi

            builtin echo $filename
    }

    ######################## Added for testing
    filename_caller(){
    builtin echo "filename_caller Call $1"
    output=$(log4bash_abs $(log4bash_filename "${log4bash_appender_f_dir}" "${log4bash_appender_f_file}" "1" "log4bash_appender_f" ))

    builtin echo ${output}
    }

    #### Previous logs generation
    for i in {1101..1120}; do
            file="${log4bash_appender_f_file}.2012${i:2:3}"
            builtin echo "${file} $i"
            touch -m -t "2012${i}0000" ${log4bash_appender_f_dir}/$file
    done

    for i in {1..4}; do
            filename_caller $i
    done

I expect log4bash_filename function to step into the following if only when the calculated log filename is different from the previous one:

if [ -n "${!maxBackupIndexVar}" ] && [ "${!previousFilenameVar}" != "${filename}" ]; then

For this scenario to apply, I'd need ${!previousFilenameVar} to be correctly set, but it's not the case, so log4bash_filename steps into this if all the time which is really not necessary...

It looks like the issue is due to the following line not working properly:

builtin eval export $previousFilenameVar=$filename

I have a some theories to explain why:

• in the original code, functions are declared and exported as readonly which makes them unable to modify global variable. I removed readonly declarations in the above sample, but probleme persists.
• Function calls are performed in $() which should make them run into seperated shell instances so variable modified are not exported to the main shell

But I cannot manage to find a workaround to this issue...

Any help is appreciated, thanks in advance!