This command will search any line in test1.txt which starts with an alphabetic word which also ends the line. This command will search the patterns ab, bc in the file test1.txt. This variant uses extended regular expressions. There are various grep implementations available in many operating systems. Overall, grep command allows searching the given regular expression and displaying the matching lines. Similarly, the following command displays 3 lines before the given string “test”. This will find the example1 files with any format.įollowing command display 2 lines after the given string “test”. This command will search the word test in both files and display the result. This command displays all the lines that start with the word test, in the example1.txt file. The grep command allows the users to scan the documents and to display the result according to the given regular expression. – Comparison of Key Differences Key Terms Overall, egrep allows searching multiple patterns at a time using a single command easily. The grep allows to search patterns using regular expressions whereas egrep allows using extended regular expressions. There is a large number of commands with options. These operating systems provide the opportunity for the users to enter commands to the Command Line Interface (CLI) to accomplish tasks. Linux is a free and open source operating system that is based on UNIX. Furthermore, it performs memory management, process handling, task scheduling and many more. It works as the interface between the user and the hardware. The operating system is the core of the entire computer system. $ egrep 'Manager|Developer' employee.The main difference between grep and egrep is that grep is a command that allows searching content according to the given regular expression and displaying the matching lines while egrep is a variant of grep that helps to search content by applying extended regular expressions to display the machining lines. You can also combine NOT with other operator to get some powerful combinations.įor example, the following will display either Manager or Developer (bot ignore Sales). i.e It matches all the lines except the given pattern.įor example, display all the lines except those that contains the keyword “Sales”. Using grep -v you can simulate the NOT conditions. The following example will grep all the lines that contain both “Manager” and “Sales” in the same line. Grep -E 'pattern1' filename | grep -E 'pattern2' You can also use multiple grep command separated by pipe to simulate AND scenario. ![]() Note: Using regular expressions in grep is very powerful if you know how to use it effectively. $ grep -E 'Manager.*Sales|Sales.*Manager' employee.txt The following example will grep all the lines that contain both “Manager” and “Sales” in it (in any order). The following example will grep all the lines that contain both “Dev” and “Tech” in it (in the same order). Grep -E 'pattern1.*pattern2|pattern2.*pattern1' filename But, you can simulate AND using grep -E option. Use multiple -e option with grep for the multiple OR patterns.ĥ. Use multiple -e option in a single command to use multiple patterns for the or condition.įor example, grep either Tech or Sales from the employee.txt file. Using grep -e option you can pass only one parameter. ![]() So, use egrep (without any option) and separate multiple patterns for the or condition. Just use the | to separate multiple OR patterns.Įgrep is exactly same as ‘grep -E’. If you use the grep command with -E option, you just need to use | to separate multiple patterns for the or condition.įor example, grep either Tech or Sales from the employee.txt file. Without the back slash in front of the pipe, the following will not work. If you use the grep command without any option, you need to use \| to separate multiple patterns for the or condition.įor example, grep either Tech or Sales from the employee.txt file. I prefer method number 3 mentioned below for grep OR operator. ![]() ![]() Use any one of the following 4 methods for grep OR. You already knew that grep is extremely powerful based on these grep command examples. The following employee.txt file is used in the following examples. The examples mentioned below will help you to understand how to use OR, AND and NOT in Linux grep command. But, you can simulate AND using patterns. Question: Can you explain how to use OR, AND and NOT operators in Unix grep command with some examples?Īnswer: In grep, we have options equivalent to OR and NOT operators.
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