shell 分割文件

标签：shell

帮同事写的小程序

140822,1406181801491716879,221.203.75.168,20140822000014
140823,1408051715321587060,101.28.174.242,20140822000127
140823,1408051715321587060,101.28.174.242,20140822000129
140824,1408051715321587060,101.28.174.242,20140822000139
140824,1406031640261808247,110.254.245.82,20140822000205
140825,1305230023521467300,210.73.6.180,20140822000216
140825,1408181402431171048,110.243.255.56,20140822000216
140825,1408131900341325654,110.248.233.239,20140822000216
140825,1407071756131811923,27.213.51.178,20140822000228
140826,1408171201311863011,124.67.26.134,20140822000238

要按不同的日期分割文件， shell脚本如下:

cat data.txt | while read line
do
if [ -n "$line" ]
then
echo $line
echo ${line%%,*}
echo $line >> "${line%%,*}.txt"
echo "${line##*,}"
fi
done

实际运行中，速度非常差，无法容忍，由于时间的起止是从140822 至  140826

所以程序改为

date
for((i=140818;i<=140826;i++));do
    echo $i;
    awk '{if(/^'$i'/)print $0;}' data.txt >$i.data.csv
done;
date

尝试使用grep替代awk命令发现速度更快

date
for((i=140818;i<=140826;i++));do
    echo $i;
    grep "$i," data.txt > "${i}.txt"
done;
date

使用awk命令耗时为6分钟左右，而使用grep 命令耗时大约为3分多钟

即使是shell命令也是非常有意思的。

shell 分割文件

标签：shell

原文地址：http://blog.csdn.net/woshiaotian/article/details/39181965