basic principles for writing bash scripts

• Use main func calling other functions
• Use functions - several commands performing an logical entity should form a function
• Try to separate the machine / host  dependant settings into a SetVars function
• Use logging , capture the commads output and log them 
• For any operation on file , string etc test first that it exists 
• have a cheat sheet open all the time from which to copy basic constructs - bash syntax is quite tricky and could bring you surprises