bash Linux 连续行之间的差异
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Linux differences between consecutive lines
提问by SYNCRo
I need to loop trough nlines of a file and for any i between 1 and n - 1to get the difference line(n - 1) - line(n).
我需要循环n一个文件的低谷行和任何一个i between 1 and n - 1以获得差异line(n - 1) - line(n)。
And here is the source file:
这是源文件：
root@syncro:/var/www# cat cron.log | grep "/dev/vda"
/dev/vda 20418M 14799M 4595M 77% /
/dev/vda 20418M 14822M 4572M 77% /
/dev/vda 20418M 14846M 4548M 77% /
/dev/vda 20418M 14867M 4527M 77% /
/dev/vda 20418M 14888M 4506M 77% /
/dev/vda 20418M 14910M 4484M 77% /
/dev/vda 20418M 14935M 4459M 78% /
/dev/vda 20418M 14953M 4441M 78% /
/dev/vda 20418M 14974M 4420M 78% /
/dev/vda 20418M 15017M 4377M 78% /
/dev/vda 20418M 15038M 4356M 78% /
root@syncro:/var/www# cat cron.log | grep "/dev/vda" | cut -b 36-42 | tr -d " M"
4595
4572
4548
4527
4506
4484
4459
4441
4420
4377
4356
those /dev/vda...lines are logged hourly with df -BMin cron.logfile and the difference between lines will reveal the hourly disk consumption.
这些/dev/vda...线以每小时记录df -BM在cron.log文件和行之间的差别将揭示每小时磁盘消耗。
So, the expected output will be:
因此，预期的输出将是：
23 (4595 - 4572)
24 (4572 - 4548)
...
43 (4420 - 4377)
21 (4377 - 4356)
I don't need the text between (and ), I put it here for explanation only.
我不需要的文本(和)，我把它放在这里仅用于说明。
回答by hek2mgl
I'm not sure if I got you correctly, but the following awkscript should work:
我不确定我是否正确理解，但以下awk脚本应该可以工作：
awk '{if(NR>1){print _n-};_n=}' your.file
Output:
输出：
23
24
21
21
22
25
18
21
43
21
You don't needthe other programs in the pipe. Just:
您不需要管道中的其他程序。只是：
awk '/\/dev\/vda/ {if(c++>0){print _n-};_n=}' src/checkout-plugin/a.txt
will be enough. The regex on start of the awkscripts tells awk to apply the following block only to lines which match the pattern. A side effect is that NRcan't be used anymore to detect the "second line" in which the calculation starts. I introduced a custome counter cfor that purpose.
就足够了。awk脚本开始时的正则表达式告诉 awk 将以下块仅应用于匹配模式的行。一个副作用是NR不能再用于检测计算开始的“第二行”。c为此，我引入了一个客户柜台。
Also note that awkwill remove the Mon it's own, because the column has been used in a numeric calculation.
另请注意，awk将M自行删除，因为该列已用于数值计算。
