Special symbols in 1.4-shell

* Wildcard #注释 \ escape Character | Pipe character $ variable character; command delimiter

!! Executes the previous command!$ the last parameter of the previous command ~ home directory & Command Background execution

> correct override redirect >> correct append redirect (cannot redirect error result)

2> Error override redirect 2>> error append redirect < reverse redirect

[] single character match range such as: [0-9a-za-z]

Special symbols in 1.4-shell