Grep multiple strings in a file11/21/2023 ![]() ![]() This can be used to specify multiple search patterns, or to protect a patternīeginning with a hyphen (-). ![]() Interpret PATTERN as an extended regular expression (ERE, see below). Selectively citing the man page of gnu-grep: -E, -extended-regexp ² while egrep has been deprecated by POSIX and is sometimes no longer found on some systems, on some other systems like Solaris when the POSIX or GNU utilities have not been installed, then egrep is your only option as its /bin/grep supports none of -e, -f, -E, \| or multi-line patterns ¹ some grep implementations support even more like perl-compatible ones with -P, or augmented ones with -X, -K for ksh wildcards. To work around that, with some grep implementations like GNU grep, you can use the -H option, or with any implementation, you can pass /dev/null as an extra argument. Note that if *.txt expands to a single file, grep won't prefix matching lines with its name like it does when there are more than one file. Or store those patterns in a file, one per line and run grep -f that-file - *.txt Or put patterns on several lines: grep - 'foo You can do this by preceding each pattern with the -e option. You need to pass the -E option to grep to select it (formerly that was done with the egrep separate command²) grep -E - 'foo|bar' *.txtĪnother possibility when you're just looking for any of several patterns (as opposed to building a complex pattern using disjunction) is to pass multiple patterns to grep. The portable way is to use the newer syntax, extended regular expressions. The old, default syntax ( basic regular expressions) doesn't support the alternation ( |) operator, though some versions have it as an extension, but written with a backslash. Second, grep supports at least¹ two syntaxes for patterns. If you do need a single quote, you can write it as '\'' (end string literal, literal quote, open string literal). (also note the - end-of-option-marker to stop some grep implementations including GNU grep from treating a file called -foo-.txt for instance (that would be expanded by the shell from *.txt) to be taken as an option (even though it follows a non-option argument here)). ![]() Single quotes prevent expansion of anything between them (including backslashes) the only thing you can't do then is have single quotes in the pattern. The easiest way to do that is to put single quotes around it. When you run this command, you'll get back a list of every line in the document containing the word bee or the word Vanessa.First, you need to protect the pattern from expansion by the shell. The syntax looks like this: grep -E 'bee|Vanessa' ~ /work/beescript.txt Let's say, for example, you wanted to find every occurrence of the words bee and Vanessa in a text document containing the script from the 2007 Bee movie. ![]() This syntax, using the ~ and /, followed by the location of the file in the home folder, is what you'll use to show the grep command which files to search. For example, if you wanted to enter the path for a text document located in a folder called work inside the home folder, you'd reference it using this format: ~ /work/textdocument.txt You'll also need to be familiar with how to reference files by path using the terminal. First, you'll need to be able to bring up a terminal-on most systems, you do this with the key combination Ctrl + Alt + T, or via the applications menu. Searching Multiple Strings in grepīefore getting started, you'll need to make sure you are familiar with a few Linux basics. This article focuses on how to search multiple strings using grep and will show you a few similar tips and tricks for using grep in general. ![]()
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |