![]() ![]() ![]() I’m sure that this tutorial would have helped you to get a good understanding of what is grep command in Unix and how it is used in various conditions. Match all lines that contain the word hello in upper-case or lower-case.Match all lines that start with a digit following zero or more spaces.Match all lines that do not contain a vowel.Match all lines that contain any of the letters ‘a’, ‘b’, ‘c’, ‘d’ or ‘e’.Match all lines that start with ‘hello’. ![]() -c: displays the count of the matching patterns.-v: displays the lines not containing the specified pattern.He enjoys writing on Linux and Python as well as contributing to open-source projects. The two lines that successfully match the pattern have been displayed to the standard terminal. One of those alien technologies that take weeks and months to learn. It means that the grep command should look for lines in the delft.txt file that ends with the string pattern rd. -n: displays the lines containing the pattern along with the line numbers. It looks like one of those acronyms for programmers.-i: performs a case-insensitive search.The grep command supports a number of options for additional controls on the matching: #5) Repetition Modifier: A ‘*’ after a character or group of characters is used to allow matching zero or more instances of the preceding pattern. “” will match all lines that do not contain x, y or z. A carat can be used at the beginning of the range to specify a negative range. E.g.“” will match all lines that contain a digit. A hyphen can be used while specifying a range to shorten a set of consecutive characters. #4) Character Range: A set of characters enclosed in a ‘’ pair specify a range of characters to be matched.Įxample: “” will match all lines that contain a vowel. #3) Escaped Characters: Any of the special characters can be matched as a regular character by escaping them with a ‘\’.Įxample: “\$\*” will match the lines that contain the string “$*” #2) Wildcard Character: ‘.’ Is used to match any character.Įxample: “^.$” will match all lines with any single character. The strings “\” are used to anchor the pattern to the start and end of a word respectively. #1) Anchor Characters: ‘^’ and ‘$’ at the beginning and end of the pattern are used to anchor the pattern to the start of the line, and to the end of the line respectively.Įxample: “^Name” matches all lines that start with the string “Name”. Special characters are used to define the matching rules and positions. A regular expression is a string of characters that is used to specify a pattern matching rule. The pattern is specified as a regular expression. ![]()
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