Metacharacters in perl are as follows:
^ means the beginning of a line;
$ means the end of a line;
( ) means a matching block, the matching block can be read through $1, $2..., but cannot be written; $0 means this perl file
\ means for escaping, such as \n means newline;
| Indicates that when perl matches, the logical rank is relatively low;
@ represents the value of an array;
[ means the meaning of [];
{ Indicates the meaning of {} the entire pattern;
? Indicates that the preceding character appears 1 or 0 times;
. Represents any character, except \n newline character, if it is modified with /s, then \n can be matched;
+ means that the preceding character appears at least once;
* means that the preceding character appears at least 0 times;
Other characters can be escaped without \.