move shell scripts and zsh and add fav vscode themes

shell/shell_scripts/lessons/TRICKS.md

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+Wild Cards
+----------
+
+Use *, ? (for one char), and [abc] for a series of options. Example:
+
+$ ls [abc]*
+
+
+More commands on one line
+-------------------------
+
+Use ;
+$ date;who
+
+
+Redirection of Standard output/input
+-----------------------------------
+
+>, >>, <
+
+Examples:
+
+$ sort < filename > sorted_names
+
+
+Pipes
+-----
+A pipe is nothing but a temporary storage place where the output of one command is stored and then passed as the input for second command.
+
+
+Processes and PID
+-----------------
+An instance of running command is called process and the number printed by shell is called process-id (PID), this PID can be use to refer specific running process.
+
+ps - show current running
+kill {PID} - kill process
+kill 0 - stop all processes except shell
+& - background process
+ps aux - display the owner of the processes along with the processes
+ps -ag - get information of all running processes
+ps ax | grep processes-you-want-to-see
+top - see currently running processes and other information like memory and CPU
+pstree - display a tree of processes
+
+
+
+Useful Cmds:
+------------
+
+List size of folders
+$ du -sh *
+
+Print calendar:
+$ cal
+
+Writing and creating a file:
+$ cat > NEWFILE
+
+--- write here ---
+^D
+
+
+De-bug Shell Script
+-------------------
+
+Use -v and -x option:
+$ sh option SCRIPT
+$ bash option SCRIPT
+
+
+Local and Global Variables
+-------------------------
+
+Whenever you type:
+$ /bin/bash
+You start a new shell where the previous variables will be forgotten (local variables). To make variables global, you can do:
+$ export VARIABLE-NAME
+Before changing shell.
+
+
+Conditional Execution
+---------------------
+
+The control operators are && (AND) and || (OR).
+$ rm myf && echo "File is removed successfully" || echo "File is not removed"
+
+
+Functions
+---------
+
+$ SayHello()
+{
+   echo "Hello $LOGNAME, Have nice computing"
+   return
+}
+To execute this SayHello() function just type it name as follows:
+$ SayHello