diff --git a/README.md b/README.md
index ba5842b..0965125 100644
--- a/README.md
+++ b/README.md
@@ -13,10 +13,35 @@ Ctrl + e : move to the end of line.
 Ctrl + w : cut the word before the cursor; then Ctrl + y paste it
 Ctrl + u : cut the line; then Ctrl + y paste it
 Ctrl + x + Ctrl + e : launch editor defined by $EDITOR to input your command. Useful for multi-line commands.
+
+Esc + c : converts letter under the cursor to uppercase, rest of the word to lowercase.
 ```
 
-### ... With My Own Configuration
+### ... with my own configuration
 
 ```
 Ctrl + t : print current date
+```
+
+###  environment variables
+
+```
+$0   : name of shell or shell script.
+$1, $2, $3, ... : positional parameters.
+$#   : number of positional parameters.
+$?   : most recent foreground pipeline exit status.
+$-   : current options set for the shell.
+$$   : pid of the current shell (not subshell).
+$!   : is the PID of the most recent background command.
+
+$USER     : current username
+$HOSTNAME : current hostname
+```
+
+### length of variable
+
+```
+var="some string"
+echo ${#var}
+# 11
 ```
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