diff --git a/sources/tech/awk/Part 2 - How to Use Awk to Print Fields and Columns in File.md b/sources/tech/awk/Part 2 - How to Use Awk to Print Fields and Columns in File.md deleted file mode 100644 index 50212c7931..0000000000 --- a/sources/tech/awk/Part 2 - How to Use Awk to Print Fields and Columns in File.md +++ /dev/null @@ -1,107 +0,0 @@ -[Cathon is translating] -How to Use Awk to Print Fields and Columns in File -====================================================== - -In this part of our Linux Awk command series, we shall have a look at one of the most important features of Awk, which is field editing. - -It is good to know that Awk automatically divides input lines provided to it into fields, and a field can be defined as a set of characters that are separated from other fields by an internal field separator. - -![](http://www.tecmint.com/wp-content/uploads/2016/04/Awk-Print-Fields-and-Columns.png) ->Awk Print Fields and Columns - -If you are familiar with the Unix/Linux or do [bash shell programming][1], then you should know what internal field separator (IFS) variable is. The default IFS in Awk are tab and space. - -This is how the idea of field separation works in Awk: when it encounters an input line, according to the IFS defined, the first set of characters is field one, which is accessed using $1, the second set of characters is field two, which is accessed using $2, the third set of characters is field three, which is accessed using $3 and so forth till the last set of character(s). - -To understand this Awk field editing better, let us take a look at the examples below: - -**Example 1**: I have created a text file called tecmintinfo.txt. - -``` -# vi tecmintinfo.txt -# cat tecmintinfo.txt -``` - -![](http://www.tecmint.com/wp-content/uploads/2016/04/Create-File-in-Linux.png) ->Create File in Linux - -Then from the command line, I try to print the first, second and third fields from the file tecmintinfo.txt using the command below: - -``` -$ awk '//{print $1 $2 $3 }' tecmintinfo.txt -TecMint.comisthe -``` - -From the output above, you can see that the characters from the first three fields are printed based on the IFS defined which is space: - -- Field one which is “TecMint.com” is accessed using `$1`. -- Field two which is “is” is accessed using `$2`. -- Field three which is “the” is accessed using `$3`. - -If you have noticed in the printed output, the field values are not separated and this is how print behaves by default. - -To view the output clearly with space between the field values, you need to add (,) operator as follows: - -``` -$ awk '//{print $1, $2, $3; }' tecmintinfo.txt - -TecMint.com is the -``` - -One important thing to note and always remember is that the use of `($)` in Awk is different from its use in shell scripting. - -Under shell scripting `($)` is used to access the value of variables while in Awk `($)` it is used only when accessing the contents of a field but not for accessing the value of variables. - -**Example 2**: Let us take a look at one other example using a file which contains multiple lines called my_shoping.list. - -``` -No Item_Name Unit_Price Quantity Price -1 Mouse #20,000 1 #20,000 -2 Monitor #500,000 1 #500,000 -3 RAM_Chips #150,000 2 #300,000 -4 Ethernet_Cables #30,000 4 #120,000 -``` - -Say you wanted to only print `Unit_Price` of each item on the shopping list, you will need to run the command below: - -``` -$ awk '//{print $2, $3 }' my_shopping.txt - -Item_Name Unit_Price -Mouse #20,000 -Monitor #500,000 -RAM_Chips #150,000 -Ethernet_Cables #30,000 -``` - -Awk also has a `printf` command that helps you to format your output is a nice way as you can see the above output is not clear enough. - -Using `printf` to format output of the Item_Name and Unit_Price: - -``` -$ awk '//{printf "%-10s %s\n",$2, $3 }' my_shopping.txt - -Item_Name Unit_Price -Mouse #20,000 -Monitor #500,000 -RAM_Chips #150,000 -Ethernet_Cables #30,000 -``` - -### Summary -Field editing is very important when using Awk to filter text or strings, it helps you get particular data in columns in a list. And always remember that the use of `($)` operator in Awk is different from that in shell scripting. - -I hope the article was helpful to you and for any additional information required or questions, you can post a comment in the comment section. - --------------------------------------------------------------------------------- - -via: http://www.tecmint.com/awk-print-fields-columns-with-space-separator/ - -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/ -[1]: http://www.tecmint.com/category/bash-shell/ diff --git a/translated/tech/Part 2 - How to Use Awk to Print Fields and Columns in File.md b/translated/tech/Part 2 - How to Use Awk to Print Fields and Columns in File.md new file mode 100644 index 0000000000..c0b526b925 --- /dev/null +++ b/translated/tech/Part 2 - How to Use Awk to Print Fields and Columns in File.md @@ -0,0 +1,106 @@ +如何使用 Awk 输出文本中的字段和列 +====================================================== + +在 Awk 系列的这一节中，我们将看到 Awk 最重要的特性之一，字段编辑。 + +需要知道的是，Awk 能够自动将输入的行，分隔为若干字段。每一个字段就是一组字符，它们和其他的字段由一个内部字段分隔符分隔开来。 + +![](http://www.tecmint.com/wp-content/uploads/2016/04/Awk-Print-Fields-and-Columns.png) +>Awk Print Fields and Columns + +如果你熟悉 Unix/Linux 或者使用 [bash 脚本][1]编过程，那么你应该知道什么是内部字段分隔符（IFS）变量。Awk 中默认的 IFS 是制表符和空格。 + +Awk 中的字段分隔符的工作流程如下：当读到一行输入时，将它按照指定的 IFS 分割为不同字段，第一组字符就是字段一，可以通过 $1 来访问，第二组字符就是字段二，可以通过 $2 来访问，第三组字符就是字段三，可以通过 $3 来访问，以此类推，直到最后一组字符。 + +为了更好地理解 Awk 的字段编辑，让我们看一个下面的例子： + +**例 1**：我创建了一个名为 tecmintinfo.txt 的文本文件。 + +``` +# vi tecmintinfo.txt +# cat tecmintinfo.txt +``` + +![](http://www.tecmint.com/wp-content/uploads/2016/04/Create-File-in-Linux.png) +>在 Linux 上创建一个文件 + +然后在命令行中，我试着使用下面的命令从文本 tecmintinfo.txt 中输出第一个，第二个，以及第三个字段。 + +``` +$ awk '//{print $1 $2 $3 }' tecmintinfo.txt +TecMint.comisthe +``` + +从上面的输出中你可以看到，前三个字段的字符是以空格为分隔符输出的： + +- 字段一是 “TecMint.com”，可以通过 `$1` 来访问。 +- 字段二是 “is”，可以通过 `$2` 来访问。 +- 字段三是 “the”，可以通过 `$3` 来访问。 + +如果你注意观察输出的话可以发现，输出的字段值并没有被分隔开，这是 print 函数默认的行为。 + +为了使输出看得更清楚，输出的字段值之间使用空格分开，你需要添加 (,) 操作符。 + +``` +$ awk '//{print $1, $2, $3; }' tecmintinfo.txt + +TecMint.com is the +``` + +需要记住而且非常重要的是，`($)` 在 Awk 和在 shell 脚本中的使用是截然不同的！ + +在 shell 脚本中，`($)` 被用来获取变量的值。而在 Awk 中，`($)` 只有在获取字段的值时才会用到，不能用于获取变量的值。 + +**例 2**：让我们再看一个例子，用到了一个名为 my_shoping.list 的包含多行的文件。 +``` +No Item_Name Unit_Price Quantity Price +1 Mouse #20,000 1 #20,000 +2 Monitor #500,000 1 #500,000 +3 RAM_Chips #150,000 2 #300,000 +4 Ethernet_Cables #30,000 4 #120,000 +``` + +如果你只想输出购物清单上每一个物品的`单价`，你只需运行下面的命令： + +``` +$ awk '//{print $2, $3 }' my_shopping.txt + +Item_Name Unit_Price +Mouse #20,000 +Monitor #500,000 +RAM_Chips #150,000 +Ethernet_Cables #30,000 +``` + +可以看到上面的输出不够清晰，Awk 还有一个 `printf` 的命令，可以帮助你将输出格式化。 + +使用 `printf` 来格式化 Item_Name 和 Unit_Price 的输出： + +``` +$ awk '//{printf "%-10s %s\n",$2, $3 }' my_shopping.txt + +Item_Name Unit_Price +Mouse #20,000 +Monitor #500,000 +RAM_Chips #150,000 +Ethernet_Cables #30,000 +``` + +### 总结 + +使用 Awk 过滤文本或字符串时，字段编辑的功能是非常重要的。它能够帮助你从一个表的数据中得到特定的列。一定要记住的是，Awk 中 `($)` 操作符的用法与其在 shell 脚本中的用法是不同的！ + +希望这篇文章对您有所帮助。如有任何疑问，可以在评论区域发表评论。 + +-------------------------------------------------------------------------------- + +via: http://www.tecmint.com/awk-print-fields-columns-with-space-separator/ + +作者：[Aaron Kili][a] +译者：[Cathon](https://github.com/Cathon) +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/ +[1]: http://www.tecmint.com/category/bash-shell/