From 829ed85c8e1e7b09b840417f4959eebd9184e9c3 Mon Sep 17 00:00:00 2001 From: kokialoves <498497353@qq.com> Date: Wed, 29 Jun 2016 15:23:36 +0800 Subject: [PATCH] =?UTF-8?q?Delete=20Part=206=20-=20How=20to=20Use=20?= =?UTF-8?q?=E2=80=98next=E2=80=99=20Command=20with=20Awk=20in=20Linux.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...to Use ‘next’ Command with Awk in Linux.md | 76 ------------------- 1 file changed, 76 deletions(-) delete mode 100644 sources/tech/awk/Part 6 - How to Use ‘next’ Command with Awk in Linux.md diff --git a/sources/tech/awk/Part 6 - How to Use ‘next’ Command with Awk in Linux.md b/sources/tech/awk/Part 6 - How to Use ‘next’ Command with Awk in Linux.md deleted file mode 100644 index 5ae8cca086..0000000000 --- a/sources/tech/awk/Part 6 - How to Use ‘next’ Command with Awk in Linux.md +++ /dev/null @@ -1,76 +0,0 @@ -[translating]How to Use ‘next’ Command with Awk in Linux -============================================= - -![](http://www.tecmint.com/wp-content/uploads/2016/06/Use-next-Command-with-Awk-in-Linux.png) - -In this sixth part of Awk series, we shall look at using `next` command, which tells Awk to skip all remaining patterns and expressions that you have provided, but instead read the next input line. - -The `next` command helps you to prevent executing what I would refer to as time-wasting steps in a command execution. - -To understand how it works, let us consider a file called food_list.txt that looks like this: - -``` -Food List Items -No Item_Name Price Quantity -1 Mangoes $3.45 5 -2 Apples $2.45 25 -3 Pineapples $4.45 55 -4 Tomatoes $3.45 25 -5 Onions $1.45 15 -6 Bananas $3.45 30 -``` - -Consider running the following command that will flag food items whose quantity is less than or equal to 20 with a `(*)` sign at the end of each line: - -``` -# awk '$4 <= 20 { printf "%s\t%s\n", $0,"*" ; } $4 > 20 { print $0 ;} ' food_list.txt - -No Item_Name Price Quantity -1 Mangoes $3.45 5 * -2 Apples $2.45 25 -3 Pineapples $4.45 55 -4 Tomatoes $3.45 25 -5 Onions $1.45 15 * -6 Bananas $3.45 30 -``` - -The command above actually works as follows: - -- First, it checks whether the quantity, fourth field of each input line is less than or equal to 20, if a value meets that condition, it is printed and flagged with the `(*)` sign at the end using expression one: `$4 <= 20` -- Secondly, it checks if the fourth field of each input line is greater than 20, and if a line meets the condition it gets printed using expression two: `$4 > 20` - -But there is one problem here, when the first expression is executed, a line that we want to flag is printed using: `{ printf "%s\t%s\n", $0,"**" ; }` and then in the same step, the second expression is also checked which becomes a time wasting factor. - -So there is no need to execute the second expression, `$4 > 20` again after printing already flagged lines that have been printed using the first expression. - -To deal with this problem, you have to use the `next` command as follows: - -``` -# awk '$4 <= 20 { printf "%s\t%s\n", $0,"*" ; next; } $4 > 20 { print $0 ;} ' food_list.txt - -No Item_Name Price Quantity -1 Mangoes $3.45 5 * -2 Apples $2.45 25 -3 Pineapples $4.45 55 -4 Tomatoes $3.45 25 -5 Onions $1.45 15 * -6 Bananas $3.45 30 -``` - -After a single input line is printed using `$4 <= 20` `{ printf "%s\t%s\n", $0,"*" ; next ; }`, the `next` command included will help skip the second expression `$4 > 20` `{ print $0 ;}`, so execution goes to the next input line without having to waste time on checking whether the quantity is greater than 20. - -The next command is very important is writing efficient commands and where necessary, you can always use to speed up the execution of a script. Prepare for the next part of the series where we shall look at using standard input (STDIN) as input for Awk. - -Hope you find this how to guide helpful and you can as always put your thoughts in writing by leaving a comment in the comment section below. - --------------------------------------------------------------------------------- - -via: http://www.tecmint.com/use-next-command-with-awk-in-linux/ - -作者：[Aaron Kili][a] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: http://www.tecmint.com/author/aaronkili/