ubuntu permission command

ubuntu/README.md

@@ -50,7 +50,8 @@ $ sudo usermod -aG docker ${USER}
 // excecute, read, write
 $ chmod 777 filename
 
-//
+// made executable
+$ chmod +x envtest.sh
 ```
 
 ## node version manager [nvm](https://github.com/nvm-sh/nvm)
@@ -95,3 +96,54 @@ $ ssh-copy-id -i abc@host
 
 ```
 
+* environments
+
+```shell
+// add global variable
+// method1 : cli
+$ export VARNAME="value"
+$ set VARNAME="Value"
+
+// add local variable
+$ VARNAME=Value
+
+// remove
+$ unset VARNAME
+$ VARNAME=''
+
+// user wide env
+$ sudo vi ~/.bashrc
+
+..
+export NAME=Value
+...
+
+// system wide ENV file
+$ nano /etc/environment
+
+// reload a file
+$ source /etc/bash.bashrc
+
+// show a variable
+$ echo $VARNAME
+
+// show all variables
+$ printenv | sort | less
+$ env | grep GNOME
+
+$ myvar=(first second third)
+$ echo ${myvar[2]}
+third
+$ echo ${myvar[*]}
+first second third
+
+```
+
+* startup file execution order from login shell
+  * `/etc/profile`
+  * `$HOME/.bash_login`
+  * `$HOME/.bash_profile`
+  * `$HOME/.profile`
+
+* startup file from interactive shell
+  * `.bashrc` instead of `/etc/profile`