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Erwin Smith. There could be situations wherein you might want to search multiple patterns in a given file or set of files. In such scenarios, you should use the ' -e' command-line option that grep provides. For example, suppose you want to search for words "how", "to", and "forge" in all the text files present in your current working directory, then here's how you can do this:. The ' -e' command-line option also helps in scenarios wherein the pattern begins with a hyphen -. For example, if you want to search for, say, "-how", then the following command won't be helpful:.
It's when you use the -e command-line option, the command understands what exactly you are trying to search in this case:. In case you want to limit the grep output to a particular number of lines, you can do that using the ' -m' command-line option. For example, suppose you want to search for the word "how" in testfile1. But the requirement is for grep to stop searching after 3 lines containing the searched pattern have been found.
So, to do this, you can run the following command:. So for example, if you have a bash script that has a loop, and you want to fetch one match per loop iteration, then using 'grep -m1' will do the needful. If you want, you can also make the grep command obtain patterns from a file.
The tool's -f command-line option lets you do this. For example, suppose you want to search all the. Up until now, we have seen that by default grep matches and displays complete lines that contain search patterns.
But if the requirement is to make grep only display those lines that completely match the searched pattern, then this can be done using the '-x' command-line option.
And the pattern you want to search is "how are you? So to make sure that grep only displays lines that completely match this pattern, use it in the following way:.
There might be situations wherein you don't need the grep command to produce anything in the output. Instead, you just want to know whether or not a match was found based on the command's exit status. This can be achieved using the -q command-line option. In the case of grep, the command exits with '0' status when it's successful meaning, a match was found , while it exits with status '1' when no match was found. By default, the grep command displays the name of files containing the search pattern as well as matched lines.
This is quite logical, as that's what expected of this tool. However, there might be cases wherein the requirement could be to get names of those files that do not contain the searched pattern.
This is also possible with grep - the -L options lets you do this. So, for example, to find all those text files in the current directory that does not contain the word "how", you can run the following command:. If you want, you can also force grep to mute any error messages it displays in the output. This can be done using the -s command line option. As clear from the example used in the previous point, the grep command doesn't do a recursive search by default. To make sure your grep search is recursive, use the -d command-line option and pass the value 'recurse' to it.
To list all switches details use grep --help command. Save my name, email, and website in this browser for the next time I comment. Facebook Twitter Instagram. TecAdmin Home Ubuntu Home » Linux Commands » How to find all files containing specific text in Linux. Previous Article Ubuntu Related Posts.
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