gawk: SVR4

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1 A.2 Changes Between SVR3.1 and SVR4
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1 The System V Release 4 (1989) version of Unix 'awk' added these features
1 (some of which originated in 'gawk'):
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1    * The 'ENVIRON' array (⇒Built-in Variables)
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1    * Multiple '-f' options on the command line (⇒Options)
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1    * The '-v' option for assigning variables before program execution
1      begins (⇒Options)
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1    * The '--' signal for terminating command-line options
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1      Sequences::)
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1      Numeric Functions::)
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1    * The 'toupper()' and 'tolower()' built-in string functions for case
1      translation (⇒String Functions)
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1    * A cleaner specification for the '%c' format-control letter in the
1      'printf' function (⇒Control Letters)
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1    * The ability to dynamically pass the field width and precision
1      Control Letters::)
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1    * The use of regexp constants, such as '/foo/', as expressions, where
1      they are equivalent to using the matching operator, as in '$0 ~
1      /foo/' (⇒Using Constant Regexps)
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1    * Processing of escape sequences inside command-line variable
1      assignments (⇒Assignment Options)
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