![]() Only at the beginning of the document (as opposed to ^, which matches at the bginning of the document and also at the beginning of each line)Īny word boundary, defined as any position between a \w character and a \W character, in either orderĪt the end of the document (as opposed to $, which matches at the end of the document, but also at the end of each line)Īt the end of the document, or before a trailing return at the end of the document, if there is oneĮxamples (the text matched by the pattern is underlined)Ĭharacter Classes Match Sets or Ranges of Characters The pattern will only match the second line. The character class construct lets you specify a set or a range of characters to match, or to ignore. A character class is constructed by placing a pair of square brackets around the group or range of characters you wish to include. To exclude, or ignore, all characters specified by a character class, add a caret character ^ just after the opening bracket. You can use any number of characters or ranges between the brackets. Here are some examples:Īny character that is neither a vowel nor a digitĬharacter classes respect the setting of the Case Sensitive checkbox in the Find dialog. ![]() Will only match "a" if Case Sensitive is off,Ī character class matches when the search encounters any one of the characters in the pattern. ![]() instead of any character).However, the contents of a set are only treated as separate characters, not as words. With any modern grep implementation, you can also do: grep -F README.mdįor a fixed-string search (where. With that same implementation, wildcard matching can also be enabled within extended ( -E), augmented ( -X) or perl-like ( -P) regular expressions with the (?K) operator (and \(?K\) in basic regular expressions which actually breaks POSIX conformance, so I wouldn't rely on it as it could be removed in a future version). To match on lines that contain README.md. So with that grep implementation, you can do: grep -K 'README.md' With ast-open grep, which is also ksh93's grep builtin (not always built-in by default, and you need to enable it by putting /opt/ast/bin ahead of $PATH), you can use the -K option for grep to use shell wildcards (extended ksh93 ones). Would again be the same as: grep 'README\.md'Īs grep looks for a match within the line as opposed to finding lines that match the pattern exactly (for which you need -x). ![]() The * wildcard operator which matches on 0 or more characters can be written. Here, it seems you're confusing regular expressions with shell wildcard patterns. (the ^s showing what within the line is matched by the regular expression, which you could see with -color) Since any number includes 0, that's functionally equivalent to grep '*README.m' (which would make no difference to which lines are being matched, only on what may be matched within the line (which would show with the -color option of GNU grep for instance)).įor instance, it would match on those 2 lines: *README mike regexp operator) followed by m followed by any number of ds. So grep '*README.md*' matches on lines that contain a literal * followed by README followed by any single character (the. In BREs, when at the start of the pattern or when following the ^ or \( regexp operators, it matches a literal * only (it's also taken literally inside bracket expressions). * is a regexp operator that matches 0 or more of the preceding atom. Grep patterns are regular expressions (aka regex, regexp, RE), basic regular expressions (BRE) unless one of -E/ -F/ -P/ -K/ -X option (only the first two of which being standard) is used.
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