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This article is about how to get awk to use the Shell variable. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

There are two possible ways for awk to use the shell variable:

1. Use Shell references

Let's use an example to demonstrate how to use a shell reference instead of a shell variable in an awk command. In this example, we want to search for a user name in the file / etc/passwd, filter and output the user's account information.

Therefore, we can write a test.sh script with the following contents:

#! / bin/bash # read the user name read-p "Please enter the user name:" username # search for the user name in / etc/passwd, and then output the details cat / etc/passwd on the screen | awk "/ $username/"'{print $0}'

Then, save the file and exit.

Description of the awk command in the above test.sh script:

Cat / etc/passwd | awk "/ $username/" {print $0}'

"/ $username/": this shell reference is used to replace the value of the shell variable username in the awk command. The value of username is the pattern to search for in the file / etc/passwd.

Notice that the double quotation marks are outside the awk script'{print $0}'.

Next, add executable permissions to the script and run it, as follows:

$chmod + x test.sh $. / text.sh

After running the script, it will prompt you to enter a user name, and then you enter a valid user name and enter enter. You will see detailed user account information from the / etc/passwd file, as shown in the following figure:

Shell script to find the user name in the Password file

two。 Using awk for variable assignment

Compared with the method described above, this method is more simple and better. Considering the example above, we can run a simple command to accomplish the same task. In this method, we use the-v option to assign the value of a shell variable to an awk variable.

First, create a shell variable username, and then give it a name that we want to search in the / etc/passwd file.

Username= "aaronkilik"

Then enter the following command and enter:

# cat / etc/passwd | awk-v name= "$username"'$0 ~ name {print $0}'

Use awk to find the user name in the Password file

Description of the above command:

One of the-v:awk options to declare a variable

Username: is the shell variable

Name: is the awk variable

Let's take a closer look at $0 ~ name in the awk script'$0 ~ name {print $0}'. Remember, when we introduced the awk comparison operator in Section 4 of the awk series, value ~ pattern is one of the comparison operators, which means that if value matches pattern, true is returned.

The output ($0) passed to awk by the cat command matches the pattern (aaronkilik), which is the name we searched for in / etc/passwd, * *, and the comparison operation returns true. Next, a line containing the user's account information is output on the screen.

Thank you for reading! This is the end of the article on "how to make awk use Shell variables". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it out for more people to see!

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