To see three lines after a match: $ grep Baz -A3 metasyntactic.listĪnd to see two lines both before and after a match: $ grep -C2 metasyntactic.list -context (or -C) displays a specified number of lines before and after your matchįor example, to see two lines before a matched pattern: $ grep Baz -B2 metasyntactic.list.-before-context (or -B) displays a specified number of lines before your match.-after-context (or -A) displays a specified number of lines after your match.There’s a trio of options for doing this, and they’re as easy to remember as A-B-C (literally): For example: $ grep -only-matching -line-number Fedora example.txtĪ common way to get context about how-or why-a pattern appears in a file is to view the line above the match, or the line just after it, or both. For added context, use the -line-number option ( -n for short) to see the line number where the matched pattern appears in the file. The -only-matching (or -o for short) grep option prints only the matching part of a line. If your text file has extra long lines, then your results can contain a lot more data than you anticipate since grep doesn’t lift the string out of context. Yet, you can use a command such as strings to extract just the binary file’s plain text, and then use grep on the results like this: $ strings example.xcf | grep gimpĪ line of text is considered a string of characters terminating with a new line character-specifically, 0x0D0A or \r\n, the carriage return (CR) and line feed (LF) ASCII characters respectively. For instance, you can’t normally grep through a binary file, since binary files don’t contain much raw text. This tactic also enables grep to be used in situations when it otherwise might not be effective. For example, this command searches for iana only in the last 10 lines of 's source code, instead of searching the whole page: $ curl | tail | grep iana One is helping to narrow grep's scope by searching through only the results of another process. Here’s an example: $ grep BSD example.txtĪnother common way to use grep is with a pipe, making it a sort of filter. The canonical use of grep is searching for a precise string of characters in some greater body of text, and returning the line or lines containing successful matches. GNU grep is available from OpenCSW.Īnd finally, you can get grep and many more commands on Windows by installing the open source Cygwin package, which provides a vast collection of GNU and open source tools.
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