Linux bash syntax

  Parameters    Shell parameters
  Variables     Environment variables
  Arrays        Array Variables
  Redirection   Spooling to and from files
  Pipes         Redirect the output from one command as input for another

Looping constructs:

  IF THEN ELSE Conditional Execution
  if           Conditionally perform a command
  for          Expand words, and execute commands
  until        Execute commands (until error) 
  while        Execute commands

The break and continue builtins may be used to control loop execution.

Evaluating expressions:

  Using brackets to Group and expand expressions
  Conditional expressions
  Arithmetic expressions
  Escape Chars, delimiters and Quotes
  Command Substitution

Working with the bash Shell:

  vi editor     A one page reference to the vi editor
  Keyboard      Cursor control - Cut & paste 
  Job Control   Suspend and resume a process
  Prompt        Prompt variable
  ###           Comment / Remark
  Scripts       Writing Shell Scripts
  BashBangSplat Pronunciation guide for unix

Note that wherever a `;' appears in the description of a command's syntax, it may be replaced with one or more newlines.

For examples of all the above see my recommended Linux books