更多的正则表达式元字符
% vi textfile
Unusual occurrences happened at the fair.
Patty won fourth place in the 50 yard dash square and fair.
Occurences like this are rare.
The winning ticket is 55222.
The ticket I got is 54333 and Dee got 55544.
Guy fell down while running around the south bend in his last event.
/\<fourth\>/
需要在每一行中搜索的是所有包含单词fourth的行。\<表示的是锚定单词的开始.\>表示锚定单词的结束。被搜索的单词可以被空格分割，以标点符号结束，在一行的开始，或者在一行的未尾等等。
