So what's the best way to filter out the result? Let's say you have multiple possibilities of matching strings. Use multiple condition parameters to have an exact match So if you execute the above command, you can expect the following results: 5. This means the condition is all set for 30 to 39.Īnd one OR operator |,40 is used to look for users having age of 40.
Here, 3 means the first integer of the age should be 3 and the right next it can range from 0 to 9. Well, in that case, you can make a slight adjustment to the above command as shown: grep -E '.*,3,|,40,' data.txt
: The first bracket is a condition to look for a number that is single-digit and ranges from 0 to 9.Īnd you can expect the following result after the execution:īut what if you want to find users aged between 30-40?. *: It is used to match any character and in this case, it will print the name of the user. Looks complex? Let me break it down for you. Simple, you can use a condition that will be attached to the previous condition and look for ages less than 10 years: grep -E '.*,' data.txt So let's suppose you have data of multiple users with their name, age, and email address named as data.txt and it looks like this: John Doe,2, Īnd you want to find the data of the user with an age less than 10 years, so how would you do that? Let's say you gave instructions to match patterns in order but what if you want to add conditions in between?Īlso, I will be using AND operator here to make things easy. Let's say I want to look for a line that has Apple or pie followed by cinnamon, then, I will be using the following: grep "apple\|pie" recipes.txt | grep "cinnamon" So in that case, you can use the grep command in the following syntax: grep "String1\|String2" File.txt | grep "String3" You may want to look for multiple strings with a condition like Sting1 or String2 must be followed by the String3. Look for string1 or string2 is followed by string3 So if I were to remove space from the above command, it will look for two possibilities: Applepie or Applecider. This will instruct grep to find a string that starts immediately after the other one. If you notice closely, every option placed inside the brackets () starts with the space as in the file, they must be separated by the space.īut if you want the continuous string that combines one or the other option, you can remove the space. Similarly, you can also add options such as apple followed by pie or cider as shown in the following command: grep -n "Apple\( pie\| cider\)" recipes.txt Here, I will be using the -n option which will notify the user of the line number if the grep finds the specified string: grep "String1\(String2\)" recipes.txtįor example, here, I want to find the Apple followed by the pie in the recipes.txt, so, I used the following command: grep -n "Apple\( pie\)" recipes.txtĪnd as you can see, it gave me the output from the specified conditions and it was the first line of the file. This is one of the most useful examples, in my opinion, as I often find myself in a situation where I have to look for a string followed by the other. 
Here, I've used the -n flag which will print the number of the line from where the keyword was found. So lets I want to look for "apple" or "pear" or "mango" from the fruits.txt, then, I will be using the following command: grep -E -n"apple|mango|pear" fruits.txt Similarly, you can use the -E flag to avoid using \ to separate different patterns: grep -E "String1|String2|String3" File.txt In the above snapshot, in the left window, I have used the cat command to print the file contents and in the right window, I have used the command that gave me the output with the specific requirement. So let's say you have to look for one or the other (either this or that situation) and in that case, you can use the grep command in the following manner: grep "String1\|String2" File.txtįor example, here, I want to look for the lines containing apple or orange in the fruits.txt file, then I will be using the following: grep "apple\|orange" fruits.txt
Now, let's have a look at some practical examples. NOT ( -v): It is used when you want everything but not the output from the given pattern.OR ( | in regular expressions): It is used when you want to get results from at least one of the multiple patterns and will give you output if any of the given patterns match.* in regular expressions): It is used to search multiple patterns in a specific order and it will ensure that the given multiple patterns are in the same line. When you consider using multiple patterns with grep, you are given three operators: AND, OR, and NOT and each has a different meaning.
Grep multiple strings in same file how to#
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