File permissions by numbers

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File permissions by numbers
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Structure of a command Command name
arguments Two types of arguments Operands
The objects of the command ie, what the
command acts on. Options Specify how the
command works. All commands do not require
operands. Eg. Pwd Some commands require a
certain number of operands eg diff
  Operands are the last items in the command.
(options must precede the operand)
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Command Synopses

• Single letter options are placed together
• An option that requires an argument is separate
  from the options that dont require arguments.
• Italics or angle brackets, ltgt indicate that the
  word is a place holder. It must be replaced by an
  appropriate word.
• indicate that an argument is optional
• Indicates that two or more arguments are
  mutually exclusive.
• indicates that the previous argument can be
  repeated.

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Example

• Example
•   The synopsis of the grep command grep
• -E -F -c -l-q -insvx
  
  -e patterns
• -f patternfile ... file

•       The e option is required and it must be
  followed by a pattern
•       Either the E or F option, but not both at
  once
•       Any one of c, -l or q but not more than
  one
•       Any combination of -I, -n, -s, -v, or x
  options
•       One or more f options, but each one must
  be followed by an argument. The place holder is
  patternfile, to indicate that it is a file
  containing patterns.
•       Any number of files, indicated by file.

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