解决问题，别扩展问题

[INFO] 20180913 19:24:01.442 method start aaa
[INFO] 20180913 19:24:01.452 method start bbb
[INFO] 20180913 19:24:01.456 do something ccc
[INFO] 20180913 19:24:01.562 method end aaa
...

#!/bin/bash

# 获取准确时间的函数
function get_acc_time() {
    arr=($1)
    date_str=${arr[1]}" "${arr[2]}
    # date -d "date_str" "+%format" 可以指定输入日期，以替代默认的当前时间
    # cut 根据 '.' 切分，并取第二个字段
    echo `date -d "$date_str" "+%s"`"."`echo  ${arr[2]} | cut -d '.' -f2`
}

# 使用 -A 声明关联数组
declare -A arr_start
declare -A arr_end

# 构造开始时间数组
while read -r start_line
do
    arr_start[${arr[5]}]=`get_acc_time $start_line`
done < $start_file

# 构造结束时间数组
while read -r end_line
do
    arr_end[${arr[5]}]=`get_acc_time $end_line`
done < $end_file

# 遍历结束时间数组
for request in ${!arr_end[*]}
do
    end_time=${arr_end[$request]}
    start_time=${arr_start[$request]}
    if [ -z "$start_time" ]; then
        continue;
    fi
    # 直接使用 bc 不会显示小数点前的 0
    echo `print "%.3f" echo "scale=3;$end_time-$start_time"| bc` >> $out_file
done

开始日志 aaa bbb ccc ddd eee fff
结束日志 aaa bbb ccc ddd eee fff

#!/bin/bash

function get_acc_time() {
    date_str=$1" "$2
    acc_time=`date -d "$date_str" "+%s"`"."`echo  $2 | cut -d '.' -f2`
    echo $acc_time
}

total=`cat $end_file | wc -l`
i=0
while read -r start_line
do
    i=`expr $i + 1`
    arr_start=($start_line)

    # 如果取不到的话去下一行取
    for j in `seq $i $total`
    do
        end_line=`awk "NR==$j" $end_file` // 用 awk 直接取到第 N 行的数据
        arr_end=($end_line)

        # 判断两条日志的 unique_id 一样
        if [ "${arr_start[5]}" = "${arr_end[5]}" ];then
            break
        fi
            i=`expr $i + 1`
    done

    start_time=`get_acc_time ${arr_start[1]} ${arr_start[2]}`
    end_time=`get_acc_time ${arr_end[1]} ${arr_end[2]}`

    echo `print "%.3f" echo "scale=3;$end_time-$start_time"| bc` >> $out_file
done < $start_file

#!/bin/bash
function get_time() {
        date_str=$1" "`echo $2 | cut -d '.' -f1`
        acc_time=`date -d "$date_str" "+%s"`"."`echo  $2 | cut -d '.' -f2`
    echo $acc_time
}

SAVEIFS=$IFS # 保存系统原来的分隔符（空格）
IFS=$'\n' # 将分隔符设置为换行，这样才能将文件按行分隔为数组

start_lines=(`cat $start_file`)
end_lines=(`cat $end_file`)

total=`cat $end_file | wc -l`
i=0
IFS=$SAVEIFS # 将分隔符还设置回空格，后续使用它将每行日志切分为数组
for start_line in ${start_lines[*]}
do
    arr_start=($start_line)

    for j in `seq $i $total`
    do
        end_line=${end_lines[$j]}
        arr_end=($end_line)

        if [  -z "$end_line"  -o "${arr_start[5]}" = "${arr_end[5]}" ];then
            break
        fi
            i=`expr $i + 1`
    done

    i=`expr $i + 1`
    start_time=`get_time ${arr_start[1]} ${arr_start[2]}`
    end_time=`get_time ${arr_end[1]} ${arr_end[2]}`

    echo `print "%.3f" echo "scale=3;$end_time-$start_time"| bc` >> $out_file
done

#!/bin/bash
function get_time() {
    date_str=$1" "`echo $2 | cut -d '.' -f1`
    acc_time=`date -d "$date_str" "+%s"`"."`echo  $2 | cut -d '.' -f2`
    echo $acc_time
}

while read -r start_line
do
    arr_s=($start_line)

    start_time=`get_time ${arr_s[1]} ${arr_s[2]}`
    end_time=`get_time ${arr_s[5]} ${arr_s[6]}`

    # 每行前面输出一个 unique_id
    echo -e ${arr_s[5]}" \c" >> $out_file
    echo `print "%.3f" echo "scale=3;$end_time-$start_time"| bc` >> $out_file
done < $start_file

#!/bin/bash
while read -r start_line
do
    str=`echo "hello"`
done < $start_file