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oawk(1)								       oawk(1)

NAME    [Toc]    [Back]

     oawk - pattern scanning and processing language

SYNOPSIS    [Toc]    [Back]

     oawk [ -Fc	] [ prog ] [ parameters	] [ files ]

DESCRIPTION    [Toc]    [Back]

     oawk scans	each input file	for lines that match any of a set of patterns
     specified in prog.	 With each pattern in prog there can be	an associated
     action that will be performed when	a line of a file matches the pattern.
     The set of	patterns may appear literally as prog, or in a file specified
     as	-f file.  The prog string should be enclosed in	single quotes (') to
     protect it	from the shell.

     Parameters, in the	form x=...  y=...  etc., may be	passed to oawk.

     Files are read in order; if there are no files, the standard input	is
     read.  The	filename - means the standard input.  Each line	is matched
     against the pattern portion of every pattern-action statement; the
     associated	action is performed for	each matched pattern.

     An	input line is made up of fields	separated by white space.  (This
     default can be changed by using FS; see below).  The fields are denoted
     $1, $2, ...; $0 refers to the entire line.

     A pattern-action statement	has the	form:

	  pattern { action }

     A missing action means print the line; a missing pattern always matches.
     An	action is a sequence of	statements.  A statement can be	one of the

	  if ( conditional ) statement [ else statement	]
	  while	( conditional )	statement
	  for (	expression ; conditional ; expression )	statement
	  { [ statement	] ... }
	  variable = expression
	  print	[ expression-list ] [ >expression ]
	  printf format	[ , expression-list ] [	>expression ]
	  next # skip remaining	patterns on this input line
	  exit # skip the rest of the input

     Statements	are terminated by semicolons, new-lines, or right braces.  An
     empty expression-list stands for the whole	line.  Expressions take	on
     string or numeric values as appropriate, and are built using the
     operators +, -, *,	/, %, and concatenation	(indicated by a	blank).	 The
     Coperators	++, --,	+=, -=,	*=, /=,	and %= are also	available in
     expressions.  Variables may be scalars, array elements (denoted x[i]) or
     fields.  Variables	are initialized	to the null string.  Array subscripts

									Page 1

oawk(1)								       oawk(1)

     may be any	string,	not necessarily	numeric; this allows for a form	of
     associative memory.  String constants are quoted (").

     The print statement prints	its arguments on the standard output (or on a
     file if >expr is present),	separated by the current output	field
     separator,	and terminated by the output record separator.	The printf
     statement formats its expression list according to	the format (see

     The built-in function length returns the length of	its argument taken as
     a string, or of the whole line if no argument.  There are also built-in
     functions exp, log, sqrt, and int.	 The last truncates its	argument to an
     integer; substr(s,	m, n) returns the n-character substring	of s that
     begins at position	m.  The	function sprintf(fmt, expr, expr, ...)
     formats the expressions according to the printf(3S) format	given by fmt
     and returns the resulting string.

     Patterns are arbitrary Boolean combinations ( !, ||, &&, and parentheses)
     of	regular	expressions and	relational expressions.	 Regular expressions
     must be surrounded	by slashes and are as in egrep (see grep(1)).
     Isolated regular expressions in a pattern apply to	the entire line.
     Regular expressions may also occur	in relational expressions.  A pattern
     may consist of two	patterns separated by a	comma; in this case, the
     action is performed for all lines between an occurrence of	the first
     pattern and the next occurrence of	the second.

     A relational expression is	one of the following:

	  expression matchop regular-expression
	  expression relop expression

     where a relop is any of the six relational	operators in C,	and a matchop
     is	either ~ (for contains)	or !~ (for does	not contain).  A conditional
     is	an arithmetic expression, a relational expression, or a	Boolean
     combination of these.

     The special patterns BEGIN	and END	may be used to capture control before
     the first input line is read and after the	last.  BEGIN must be the first
     pattern, END the last.

     A single character	c may be used to separate the fields by	starting the
     program with:

	  BEGIN	{ FS = c }

     or	by using the -Fc option.

     Other variable names with special meanings	include	NF, the	number of
     fields in the current record; NR, the ordinal number of the current
     record; FILENAME, the name	of the current input file; OFS,	the output
     field separator (default blank); ORS, the output record separator
     (default new-line); and OFMT, the output format for numbers (default

									Page 2

oawk(1)								       oawk(1)


EXAMPLES    [Toc]    [Back]

     Print lines longer	than 72	characters:

	  length > 72

     Print first two fields in opposite	order:

	  { print $2, $1 }

     Add up first column, print	sum and	average:

	       { s += $1 }
	  END  { print "sum is", s, " average is", s/NR	}

     Print fields in reverse order:

	  { for	(i = NF; i > 0;	--i) print $i }

     Print all lines between start/stop	pairs:

	  /start/, /stop/

     Print all lines whose first field is different from previous one:

	  $1 !=	prev { print; prev = $1	}

     Print file, filling in page numbers starting at 5:

	  /Page/ { $2 =	n++; }
		 { print }

	  command line:	 oawk -f program n=5 input

SEE ALSO    [Toc]    [Back]

     awk(1), grep(1), lex(1), perl(1), sed(1), printf(3S).

BUGS    [Toc]    [Back]

     Input white space is not preserved	on output if fields are	involved.
     There are no explicit conversions between numbers and strings.  To	force
     an	expression to be treated as a number add 0 to it; to force it to be
     treated as	a string concatenate the null string ("") to it.

									PPPPaaaaggggeeee 3333
[ Back ]
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