![]() But what do you do when it does something you weren't expecting? Let's take a look at some of the problems you might run into. The grep command is one of the tools that makes the Unix command line powerful. We can look for numbers that have a certain number of digits or numbers that look like 88 or 123-45-6789. We can find a string irrespective of its case. With grep, we can find text literally (e.g., a name, a label) or we can find it by expressing what it looks like (e.g., dates, addresses, phone numbers).īecause grep uses regular expressions, it can accommodate a wide range of text patterns and it can anchor our searches to the beginnings or endings of lines when this is important. This fact that it works so well with regular expressions is why it comes in so handy for so many routine tasks. ![]() Grep stands for "( globally search a regular expression and print). It's one of the cornerstones of Unix and it works with regular expressions - thus, its name. Grep is not just a nice tool for grabbing lines containing specific text from arbitrary files. When you're working with big data files, on the other hand, you might have to be a lot more precise in your queries and know when to abandon grep for a more accommodating tool.įirst, understand that I have no gripes with grep. If you're working with small files, getting a few extra lines might not be a big deal. Sometimes you end up with far more matches than you expect and sometimes you get far fewer. There are times you might not get what you are looking for using the grep command.
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