![]() sudo grep -E 'string1|string2|string3' /home/nl/test.txt See the examples below to see what I mean. If you want to search for regex patterns, use -E or -e option. The syntax above only allows searching for raw strings. sudo grep 'string1|string2|string3' /home/nl/test.txt Code language: JavaScript ( javascript ) In this case, you can use only the filename in the command as you’re already in that directory. sudo grep 'string1|string2|string3' /home/nl/test.txt Code language: JavaScript ( javascript )Īlternatively, you can navigate into /home/nl and do the grep search. Suppose you want to search for multiple strings in a single file located in /home/nl/test.txt, and you want to do it in a single run, use the command below. In both cases, grep will output all the lines that might contain any of the listed patterns. command | grep 'pattern1|pattern2|.' Code language: JavaScript ( javascript ) What we’ve just did is asking grep to look for multiple patterns (pattern1, pattern2, …) in a file.Īlternatively, we can pass (pipe) the output of another command to grep to search it for required strings by running the following commands. sudo grep 'pattern1|pattern2|.' /path/to/file Code language: JavaScript ( javascript ) In other words, you have to use | instead of | in a grep command. grep use | symbol to separate two patterns in a command.īut before you actually use it, remember to escape it so that grep doesn’t mistakenly recognize it as part of the pattern. You can use the | symbol to grep multiple strings or patterns. If you want to search multiple patterns or strings in a particular file, use the grep functionality to sort within a file with the help of more than one input word in the command. In this article, we will show you how to use grep to search multiple strings and patterns at once in Linux. Ultimately, it’s up to you which of these utilities you choose to use. However, if you prefer, you can also type grep to get the same results. Out of these, fgrep is often the best option due to its speed and its focus on strings and words. There are a variety of grep utilities that can help you search through your files, including grep, egrep, and fgrep. The name, grep, derives from the command used to perform a similar operation, using the Unix/Linux text editor ed: g/re/p Grep also offers a variety of options to make your search more efficient. It’s a great way to customize your search depending on your needs. To match only specific words when matching across multiple lines you can use regular expression tools to match one words.Grep is a powerful tool that lets you search for strings, patterns, and words in files and text outputs from commands. This means that simply typing in fail will also match failure. It is important to know that the “strings” following the grep command will match the document based on the rules of regular expression. Alternatively, tools such as awk or sed will start from the first instance of from but finish at the first instance of to. This will likely affect the output you expected, especially when there may be multiple instances of from or to in your document. ![]() When using grep across multiple lines it is important to be aware that the command will get both the first instance of the from word and will get everything up until the last instance of the to word. ![]() Grep for single line to the final word in another lineĬommon “gotchas” when using grep across multiple lines grep will use the first and last instances of the words If you want to simply print out file names that have lines that have matches with the regular expression then you can alter the -o flag to -l which will list all matching file names. * will match everything, including new lines, up until to because of the addition of (?s) into the regular expression. (?s) activate PCRE_DOTALL which means that “.” finds any character or a new line.The complication however is that will also add a trailing zero byte character which can cause additional problems. -o prints only the matching strings as otherwise the entire file will be printed.Essentially this allows grep to treat the file as a whole line as opposed to multiple lines -z treats the input as a set of lines, each being terminated by a zero byte instead of a new line. ![]() -P uses Perl compatible regular expression (PCRE).This will then become available as ggrep. ![]()
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