Examination bash scripting task

#!/usr/bin/bash
#GNU bash, version 4.3.33(1)-release (x86_64-redhat-linux-gnu)

####Environment block####
param_key=$1
param_type=$2
curr_dir=`dirname "$BASH_SOURCE"`
file=$curr_dir"/GTS_LINUX-MULTI-001A.results"
fl_buff=$curr_dir"/buf_fl.tmp"
#last_buf=$curr_dir"/buf_last.tmp"
ptrn_mv_start=MEASURED_VALUE
ptrn_mv_end=MEASURED_VALUE_EOF
ln_mv_start=`grep -nw $ptrn_mv_start -F $file|awk -F : '{print $1}'`
ln_mv_end=`grep -nw $ptrn_mv_end -F $file|awk -F : '{print $1}'`
ln_indx=1
####End of environment block###

#####Function Block#####
# Function is parse file from $file variable. Any line between $ptrn_mv_start and $ptrn_mv_end would be writen to
# buffer file from $fl_buff variable.
function file_parser () {
    cat /dev/null > $fl_buff
    while read line
    do
        if [[ $ln_indx -gt $1 && $ln_indx -lt $2 ]]
        then
            echo $line >> $fl_buff
        fi
        (( ln_indx +=1 ))
    done < "$file"
}

#Function for parse buffer file from $fl_buff variable. It check parameters and do filtration of output.

function str_parser_any () {
    ###Check input parameters###
    #Checking of input parameters, sorting of output and removing of duplicates
    if [ "$1" == "-t" ]
        then
            if [ "$2" == "f" ]
                then
                    echo "Output filtered by files "
                    str_parser_f_bufer=`cat $fl_buff |  grep ^- | awk -F ";" '{print $2 "\t" $3 }' |sort -u`
            elif [ "$2" == "d" ]
                then
                    echo "Output filtered by directories "
                    str_parser_f_bufer=`cat $fl_buff |  grep ^d | awk -F ";" '{print $2 "\t" $3 }' |sort -u`
            else
                echo "Output not filtered. Use f and d keys"
                str_parser_f_bufer=`cat $fl_buff | awk -F ";" '{print $2 "\t" $3 }' |sort -u`
            fi
        else
            str_parser_f_bufer=`cat $fl_buff | awk -F ";" '{print $2 "\t" $3 }' |sort -u`
    fi
    ###End check input parameters###

    ###Checking of last login date and output to console
    buf_indx=`echo "$str_parser_f_bufer"| wc -l`
    echo "$users_lld"|
    for (( indx=1; indx <=buf_indx; indx++))
    do
        str_parser_uname=`echo "$str_parser_f_bufer"| awk "FNR == $indx {print}" | awk '{print $1}'`
        str_parser_gname=`echo "$str_parser_f_bufer"| awk "FNR == $indx {print}" | awk '{print $2}'`
        str_parser_usr_ltime=`last $str_parser_uname | head -n 1 | awk '{print $4 " " $5 " " $6 }'`
        echo "User:""$str_parser_uname" "   " "group:" "$str_parser_gname" "    " " last login at: " "$str_parser_usr_ltime"
    done
}
#####End of function block#####


######Function execution block ############
file_parser $ln_mv_start $ln_mv_end
str_parser_any $param_key $param_type
######End of function execution block #####


rm $fl_buff
exit 0