^ $ 和 a z 字符匹配

1 匹配行首   '^'   or  '\A'断言
区别：当使用m（多行）修饰符时，^匹配每行的行首，而\A仍然仅在整个字符串的开头进行匹配
eg：$_ = "this is\na multi file";
      s/^/BOL/g;   
      #BOL this is
      #BOL a multi file
      s/\A/BOL/g;
      #BOL this is
      #a multi file
2 匹配行尾 '$'   or  '\z'/'\Z'
'$' 在行尾之前进行匹配
$_ = 'Here is some text\n';
/(.*$)/;   
print "${1}."
##"Here is some text.";

/(.*$)/s;    ##用/s处理新行
print "${1}."
##
  "Here is some text
##   .";

'$'和'\z'的区别同'^' '\A'

3 '\Z' '\z' 的区别
'\z' 仅仅匹配字符串的末尾
'\Z'仅仅匹配字符串末尾或字符串末尾新行之前
$_ = "here is some text\n";
s/\z/END/;   ##匹配'\n'之前的内容
##here is some text
##END
s/\Z/END/;   ##匹配字符串结尾