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 vis(1)								      vis(1)




 NAME
      vis, inv - make unprintable and non-ASCII characters in a file visible
      or invisible

 SYNOPSIS
      vis [-n] [-s] [-t] [-u] [-x] file ...

      inv [-n] [-s] [-t] [-u] [-x] file ...

 DESCRIPTION
      vis reads characters from each file in sequence and writes them to the
      standard output, converting those that are not printable or not ASCII
      into a visible form.  inv performs the inverse function, reading
      printable characters from each file, returning them to non-printable
      or non-ASCII form, if appropriate, then writing them to standard
      output;

      Non-printable ASCII characters are represented using C-like escape
      conventions:
	   \\	   backslash
	   \b	   backspace
	   \e	   escape
	   \f	   form-feed
	   \n	   new-line
	   \r	   carriage return
	   \s	   space
	   \t	   horizontal tab
	   \v	   vertical tab
	   \n	   the character whose ASCII code is the 3-digit octal
		   number n.
	   \xn	   the character whose ASCII code is the 2-digit hexadecimal
		   number n.

      Non-ASCII single- or multi-byte characters are examined one byte at a
      time.  For each byte, if it can be displayed as an ASCII character, it
      is treated as if it is an ASCII character; Otherwise, it is
      represented in the following conventions:
	   \n	   the 8-bit character whose code value is the 3-digit octal
		   number n.
	   \xn	   the 8-bit character whose code value is the 2-digit
		   hexadecimal number n.

      Space, horizontal-tab, and new-line characters can be treated as
      printable (and therefore passed unaltered to the output) or non-
      printable depending on the options selected.  Backslash, although
      printable, is expanded by vis, to a pair of backslashes so that when
      they are passed back through inv, they convert back to a single
      backslash.

      If no input file is given, or if the argument - is encountered, vis
      and inv read from the standard input.



 Hewlett-Packard Company	    - 1 -   HP-UX Release 11i: November 2000






 vis(1)								      vis(1)




    Options
      vis and inv recognize the following options:

	   -n	   Treat new-line, space, and horizontal tab as non-
		   printable characters.  vis expands them visibly as \n,
		   \s, and \t, rather than passing them directly to the
		   output.  inv discards these characters, expecting only
		   the printable expansions.  New-line characters are
		   inserted by vis every 16 bytes so that the output will be
		   in a form that is usable by most editors.

	   -s	   Make vis and inv silent about non-existent files,
		   identical input and output, and write errors.  Normally,
		   no input file can be the same as the output file unless
		   it is a special file.

	   -t	   Treat horizontal-tab and space characters as non-
		   printable in the same manner that -n treats them.

	   -u	   Cause output to be unbuffered (byte-by-byte); normally,
		   output is buffered.

	   -x	   Cause vis output to be in hexadecimal form rather than
		   the default octal form.  Either form is accepted to inv
		   as input.

 EXTERNAL INFLUENCES
    Environment Variables
      LANG determines the language in which messages are displayed.

    International Code Set Support
      Single- and multi-byte character code sets are supported.

 AUTHOR
      vis was developed by HP.

 SEE ALSO
      cat(1), echo(1), od(1).

 WARNINGS
      Redirecting output to an input file destroys the original data.
      Therefore, command forms such as

	   vis file1 file2 >&gt&gt>file1

      should be avoided unless the source file can be safely discarded.








 Hewlett-Packard Company	    - 2 -   HP-UX Release 11i: November 2000