I have included a PDF cheatsheet which you can download, print and keep on your desk. It's good if you are already familiar with the grep command but you keep forgetting which option does what. I'll just the common options and their explanation here. Linux Handbook already has a detailed article on grep, so I won't go in depth here. This article lists the most common grep commands with quick examples. However, you'll end up using a handful of grep commands most of the time. You probably will never need or use all of them. The grep command has a huge number of options and use cases. It's especially helpful when you are troubleshooting or debugging. It is one of the most useful commands for linux administrators and you will no doubt find it useful in your administration tasks.Grep is a powerful UNIX command that lets you search inside the file contents on a variety of parameters. The -l option will then list the number of lines in the grep output.Īs you can see, grep is a powerful tool with a variety of command options and search parameters in order to return exactly the information you need. This command will look for the expression “cat” in the file named file2 and output it to the word count command wc. The output from the grep command can also be piped into another command or sent to a file depending on what you need to do with the data. The egrep command can be used to search for multiple words in a single grep search. *t will return all results that end with tĬ* will return all results that start with cĪdding quotes around a world will ensure grep only returns full word matches rather than any words that contain the search string. OptionĪn asterisk can be inserted anywhere in the expression in order to return all results with any character in the expression.Ĭ*t will return all results that begin with c and end with t, with any amount of characters in the middle. You can use various characters in order to perform more expensive or specific searches. When entering the expression to search the file for, you do not need to limit yourself to a whole or partial word. Performs a recursive search of the current directory and all sub-folders Returns all lines that do not contain the search string.įor extended expression searches. Prints the line number that the expression appeared on when outputting the command. Obtain the pattern to search from in a file. Returns results ignoring whether or not the letter is uppercase or lowercase. Here are some of the common options: OptionĬounts the number of instances of the search string in the file.ĭisplays the search results with the match search string in color.Ĭase insensitive search. There are dozens of options to choose from when executing a grep command. Performing the following command executes a case sensitive regular expression search of the file: The file named file2 has the following content: See Also: (Live Webinar) Meet ServerMania: Transform Your Server Hosting Experience How to use grep Basic SyntaxĪt its core, you can type the command grep, followed by any options associated with the command, then the pattern within the file you want to find, followed by the file name The output can also be manipulated or piped into the console depending on what you need to do with the data. The grep command searches a text file based on a series of options and search string and returns the lines of the text file which contain the matching search string. It is an open source piece of software which allows you to search within a file to find instances of a particular expression. Grep is a command included in most Linux distributions by default. In this article, we’ll outline what is grep and how to use it. Grep is one command that can be used to accomplish this task. For example, you have a long log file and want to see all the instances mentioning a specific error. There comes a time in every Linux users life where they need to find an expression within a file.
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