Grep for multiple strings in a file

Based on the error message you posted, it sounds like one or more of the 'patterns' contains some regular expression metacharacters but doesn't form a valid regular expression. Please post the offending pattern s , without that, it's impossible to tell what's going wrong. Or B Or B 1, 3 3 gold badges 21 21 silver badges 40 40 bronze badges. But what is it for anyway? Or grep -f words. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.

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Related posts:. Install Odoo with Apache Reverse Proxy. How to Mount Drive from Terminal. A regular expression is always written in a single quotation. Two names are separated with backslash and alteration operator. The command is ended with the filename. While doing grep recursive, directory or whole path is used instead of a single file name.

In this article, we will learn the functionality of grep in searching multiple patterns and strings. For this purpose, you need to have Linux operating system running on your virtual box. You need to install it on your system. After configuration, you will have access to use all applications.

After logging in to the user by providing a password, go to the terminal shell command-line to proceed. If we want to search multiple patterns or strings in a particular file, use the grep functionality to sort within a file with the help of more than one input word in the command.

The command represents how grep works. Both files mentioned will be searched in filea. Searched words are highlighted in the whole text of the output. To understand the concept of case sensitivity in grep function in Linux, consider the following example. Two commands work on grep. This example demonstrates the differences between the commands.