Regex 正規表示式 教學網站 https://likegeeks.com/regex-tutorial-linux/ http://overapi.com/regex https://regexper.com/#%2F.echo%24%2F (視覺化正規表示式) The Greatest Regex Trick Ever 測試 Regex 語法 (awk) # echo "Testing regex using awk" | awk '/regex/{print $0}' Testing regex using awk # echo "\ is a special character" | awk '/\\/{print $0}' \ is a special character # echo "likegeeks website" | awk '/^likegeeks/{print $0}' likegeeks website 基本搜尋 # 搜尋字串區分大小寫 echo "This is a test" | sed -n '/test/p' echo "This is a test" | awk '/test/{print $0}' # 可以包含空白與數字 echo "This is a test 2 again" | awk '/test 2/{print $0}' Operators Description [abc] Match any single character from from the listed characters [a-z] Match any single character from the range of characters [^abc] Match any single character not among listed characters [^a-z] Match any single character not among listed range of characters . Match any single character except a newline \ Turn off (escape) the special meaning of a metacharacter ^ Match the beginning of a line. $ Match the end of a line. * Match zero or more instances of the preceding character or regex. ? Match zero or one instance of the preceding character or regex. + Match one or more instances of the preceding character or regex. {n,m} Match a range of occurrences (at least n, no more than m) of preceding character of regex. | Match the character or expression to the left or right of the vertical bar. 數字字元 [[:digit:]]* : any number of digits (zero or more) [[:digit:]]+ : at least one digit [[:digit:]]? : zero or one digits [[:digit:]]{1,3} : at least one and no more than three digits [[:digit:]]{2,} : two or more digits [[:digit:]]{3} : three digits 特殊字元 字元:.*[]^${}\+?|() $ cat myfile There is 10$ on my pocket awk '/\$/{print $0}' myfile echo "\ is a special character" | awk '/\\/{print $0}' echo "This ^ is a test" | sed -n '/s ^/p' 搜尋字首與字尾 # 搜尋字首 $ echo "likegeeks website" | awk '/^likegeeks/{print $0}' # 搜尋字尾 $ echo "This is a test" | awk '/test$/{print $0}' # 搜尋相同字元行的文字 $ awk '/^this is a test$/{print $0}' myfile # 不顯示空白行 $ awk '!/^$/{print $0}' myfile 搜尋字串 用 dot # cat myfile this is a test This is another test And this is one more start with this # awk '/.st/{print $0}' myfile this is a test This is another test 用 [ ] // 包含 oth 與 ith $ awk '/[oi]th/{print $0}' myfile This is another test start with this // 不包含 oth 與 ith $ awk '/[^oi]th/{print $0}' myfile And this is one more start with this <== 有兩個 th 使用範圍 $ awk '/[e-p]st/{print $0}' myfile this is a test This is another test $ echo "123" | awk '/[0-9][0-9][0-9]/' $ awk '/[a-fm-z]st/{print $0}' myfile this is a test This is another test