![]() If you also want to match numbers with exponents, you can use: ? * \. We can optimize this regular expression as: ? * \. We have successfully excluded the matches we do not want: those without digits. Any match must include at least one digit. This regular expression matches an optional sign, that is either followed by zero or more digits followed by a dot and one or more digits (a floating point number with optional integer part), or that is followed by one or more digits (an integer). But it also matches many things we do not want, which we have to exclude. The above regex indeed matches a proper floating point number, because the regex engine is greedy. When creating a regular expression, it is more important to consider what it should not match, than what it should. If we had not escaped the dot, both 4.4 and 4X4 would be considered floating point numbers. A dot that is not escaped matches any character, including a dot. Not escaping the dot is also a common mistake. If you tried to use this regex to find floating point numbers in a file, you’d get a zero-length match at every position in the string where no floating point number occurs. In fact, it even considers an empty string as a valid floating point number. This regular expression considers a sign by itself or a dot by itself as a valid floating point number. Spelling out the regex in words makes it obvious: everything in this regular expression is optional. This defines a floating point number as an optional sign, followed by an optional series of digits (integer part), followed by an optional dot, followed by another optional series of digits (fraction part). We will not try to match numbers with an exponent, such as 1.5e8 (150 million in scientific notation).Īt first thought, the following regex seems to do the trick: ? * \. Our regex should also match integers and floating point numbers where the integer part is not given. As an example, we will try to build a regular expression that can match any floating point number. This example shows how you can avoid a common mistake often made by people inexperienced with regular expressions. Using sed command (any order): $ sed '/PATTERN1/!d /PATTERN2/!d' FILE GREP NOT: Negative MatchingĬool Tip: Find and validate IP addresses with grep command! The best regular expression for IP addresses! Read more →įind and print all the lines, that do not match a pattern.Matching Floating Point Numbers with a Regular Expression Using sed command (exact order): $ sed '/PATTERN1.*PATTERN2/!d' FILE Using awk command (any order): $ awk '/PATTERN1/ & /PATTERN2/' FILE Using awk command (exact order): $ awk '/PATTERN1.*PATTERN2/' FILE Using grep command (any order): $ grep -E 'PATTERN1.*PATTERN2|PATTERN2.*PATTERN1' FILEĬool Tip: The server is out of memory? Check what processes are using all the RAM and SWAP! Bash one liner for the true Linux admins! Read more → Using grep command (exact order): $ grep -E 'PATTERN1.*PATTERN2' FILE ![]() ![]() ![]() Use one of the following commands to find and print all the lines of a file, that match multiple patterns. ![]() Note, that you can both find the lines in a file that match multiple patterns in the exact order or in the any order. It is also often required to grep a file for multiple patterns – when it is needed to find all the lines in a file, that contain not one, but several patterns. Using sed command: $ sed -e '/PATTERN1/b' -e '/PATTERN2/b' -e d FILE GREP AND: Match Multiple Patterns Using awk command: $ awk '/PATTERN1|PATTERN2/' FILE Using grep and egrep commands: $ grep "PATTERN1\|PATTERN2" FILE I’ll show the examples of how to find the lines, that match any of multiple patterns, how to print the lines of a file, that match each of provided patterns and how to find and print the lines, that do not match a pattern (negative matching).Ĭool Tip: Find and validate email addresses with grep command! The best regular expression for email addresses! Read more → GREP OR: Match Any Of Multiple Patternsįind all the lines of a file, that match any of provided patterns. The grep, egrep, sed and awk are the most common Linux command line tools for parsing files.įrom the following article you’ll learn how to match multiple patterns with the OR, AND, NOT operators, using grep, egrep, sed and awk commands from the Linux command line. ![]()
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