diff --git a/README.md b/README.md
index e2a3ef3..90c2cbf 100644
--- a/README.md
+++ b/README.md
@@ -4037,9 +4037,6 @@ Inspired by RehanSaeed/
| Force redirection (even if the noclobber option is set). This will forcibly overwrite an existing file.
|
-| # |
-Comment [number sign]. Lines in files beginning with a # (with the exception of #!) are comments and will not be executed. |
-
"" |
Double quotes protects the text inside them from being split into multiple words or arguments, yet allow substitutions to occur, meaning most other special characters is usually prevented. |
@@ -4067,7 +4064,7 @@ Inspired by RehanSaeed/
| Wild card [question mark]. The ? character serves as a single-character "wild card" for filename expansion in globbing, as well as representing one character in an extended regular expression. |
{ } |
-Inline group [curly brackets]. Commands inside the curly braces are treated as if they were one command. It is convenient to use these when Bash syntax requires only one command and a function doesn't feel warranted. |
+Inline group [curly brackets]. Commands inside the curly braces are treated as if they were one command. |
| ( ) |
@@ -4079,8 +4076,76 @@ Inspired by RehanSaeed/
| [[ ]] |
-Test expression [double brackets]. It is more flexible than the single-bracket [ ] test.
+ | Test/Evaluate [double brackets] a condition expression to determine whether true or false. It is more flexible than the single-bracket [ ] test.
|
+
+| (( )) |
+Arithmetic expression [double parentheses]. Characters such as +, -, *, and / are mathematical operators used for calculations. |
+
+
+| # |
+Comment [number sign]. Lines in files beginning with a # (with the exception of #!) are comments and will not be executed. |
+
+
+| ,, , |
+Lowercase conversion in parameter substitution. |
+
+
+| ^, ^^ |
+Uppercase conversion in parameter substitution. |
+
+
+| ;; |
+Terminate [double semicolon]. Only used in case constructs to indicate the end of an alternative. |
+
+
+| $* |
+All the arguments are seen as a single word. |
+
+
+| $* |
+All the arguments that are individually double quoted and seen as a single word. |
+
+
+| !$ |
+The last argument to the previous command. |
+
+
+| !* |
+All the arguments from the previous command. |
+
+
+| $? |
+The exit status of the last command executed. |
+
+
+| $# |
+The number of arguments supplied to a script. |
+
+
+| $$ |
+The process number of the current shell. For shell scripts, this is the process ID under which they are executing. |
+
+
+| $! |
+The process number of the last background command. |
+
+
+| $- |
+Expands to the current option flags as specified upon invocation, by the set builtin command, or those set by the shell itself (such as the -i option).
+ |
+
+| $0 |
+Used to reference the name of the current shell or current shell script. |
+
+
+| $n |
+These variables correspond to the arguments with which a script was invoked. Here n is a positive decimal number corresponding to the position of an argument (the first argument is $1, the second argument is $2, and so on). |
+
+
+| $_ |
+Special variable set to final argument of previous command executed. |
+