Introduction to the functions of special characters (dollar sign, backslash, quotation mark, etc.) in shell script

Special characters in shell are 1. $Dollar Sign2. \ backslash3. ` backquote4. “Double quotes” 5、< ,>;,*,?,[,] Let me list the explanations one by one 1、 $symbol 1、echo $? Displays the exit status of the previous instruction2、echo “$?” The effect is the same as above3、echo ‘$?’ Is $?4、echo \$? Is $?5、echo “\$?” Is $? You may […]