Understanding GREP - Linux

Are you trying to search for a specific string or keyword in a file and print lines that match a pattern? The grep command can help you do just that! It searches line by line and prints lines that match the given pattern. Here are some examples of using the grep command:

• To ignore upper and lower case: use the option i followed by the keyword and the file to search.
• To search for everything except for a given pattern/keyword: use the option v followed by the keyword and the file to search.
• To print how many times the current keyword is present in a file: use the option c followed by the keyword and the file to search.
• To search for an exact match of a given keyword in a file: use the option w followed by the keyword and the file to search.
• To print the line number of matches of a given keyword in a file: use the option n followed by the keyword and the file to search.
• To search for a given keyword in multiple files: list all the files after the keyword.
• To suppress file names while searching for a given keyword in multiple files: use the option h followed by the keyword and all the files.
• To search for multiple keywords in a file: use the option e followed by each keyword separated by a space and the file to search.
• To search for multiple keywords in multiple files: use the option e followed by each keyword separated by a space and all the files to search.
• To only print file names which match a given keyword: use the option l followed by the keyword and the file to search.
• To get the keyword/pattern from one file and match it with another file: use the option f followed by the keyword/pattern file and the file to search.
• To print only the matching lines that start with a given keyword: use ^ followed by the keyword and the file to search.
• To print only the matching lines that end with a given keyword: use the keyword followed by $ and the file to search.
• If you need to search for a keyword in a large number of files in a directory: use the option R followed by the keyword and the directory to search.
• To search for multiple keywords using regular expressions: use the egrep command followed by the keywords separated by | and the file to search.
• If you just want to search but don't want to print on the terminal: use the option q followed by the keyword and the file to search.
• If you want to suppress error messages: use the option s followed by the keyword and the file to search.

As you can see, the grep command is a really handy tool with a ton of options for searching and manipulating text. Give it a try! #grep #linux #commandline #textsearch #programming