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OpenSolaris 2009.06 - man page for awk (opensolaris section 1)

awk(1)					  User Commands 				   awk(1)

NAME
       awk - pattern scanning and processing language

SYNOPSIS
       /usr/bin/awk [-f progfile] [-Fc] [' prog '] [parameters]
	    [filename]...

       /usr/xpg4/bin/awk [-FcERE] [-v assignment]... 'program' -f progfile...
	    [argument]...

DESCRIPTION
       The /usr/xpg4/bin/awk utility is described on the nawk(1) manual page.

       The  /usr/bin/awk  utility  scans each input filename for lines that match any of a set of
       patterns specified in prog. The prog string must be enclosed in single  quotes  (  a')  to
       protect it from the shell. For each pattern in prog there can be an associated action per-
       formed when a line of a filename matches the pattern. The set of pattern-action statements
       can  appear  literally  as  prog or in a file specified with the -f progfile option. Input
       files are read in order; if there are no files, the standard input is read. The file  name
       '-' means the standard input.

OPTIONS
       The following options are supported:

       -f progfile     awk uses the set of patterns it reads from progfile.

       -Fc	       Uses  the character c as the field separator (FS) character.  See the dis-
		       cussion of FS below.

USAGE
   Input Lines
       Each input line is matched against the pattern portion of every pattern-action  statement;
       the  associated	action	is  performed  for each matched pattern. Any filename of the form
       var=value is treated as an assignment, not a filename, and is  executed	at  the  time  it
       would  have  been  opened if it were a filename. Variables assigned in this manner are not
       available inside a BEGIN rule, and are assigned after previously specified files have been
       read.

       An  input  line is normally made up of fields separated by white spaces. (This default can
       be changed by using the FS built-in variable or the -Fc option.) The default is to  ignore
       leading	blanks	and to separate fields by blanks and/or tab characters. However, if FS is
       assigned a value that does not include any of the white spaces, then  leading  blanks  are
       not ignored. The fields are denoted $1, $2, ...; $0 refers to the entire line.

   Pattern-action Statements
       A pattern-action statement has the form:

	 pattern { action }

       Either  pattern	or  action  can  be  omitted. If there is no action, the matching line is
       printed. If there is no pattern, the action is performed on  every  input  line.  Pattern-
       action statements are separated by newlines or semicolons.

       Patterns  are  arbitrary  Boolean combinations ( !, ||, &&, and parentheses) of relational
       expressions and regular expressions. A relational expression is one of the following:

	 expression relop expression
	 expression matchop regular_expression

       where a relop is any of the six relational operators in C, and a matchop is either ~ (con-
       tains)  or  !~ (does not contain). An expression is an arithmetic expression, a relational
       expression, the special expression

	 var in array

       or a Boolean combination of these.

       Regular expressions are as in egrep(1). In patterns they must be  surrounded  by  slashes.
       Isolated  regular  expressions  in a pattern apply to the entire line. Regular expressions
       can also occur in relational expressions. A pattern can consist of two patterns	separated
       by  a comma; in this case, the action is performed for all lines between the occurrence of
       the first pattern to the occurrence of the second pattern.

       The special patterns BEGIN and END can be used to capture control before the  first  input
       line  has  been	read and after the last input line has been read respectively. These key-
       words do not combine with any other patterns.

   Built-in Variables
       Built-in variables include:

       FILENAME     name of the current input file

       FS	    input field separator regular expression (default blank and tab)

       NF	    number of fields in the current record

       NR	    ordinal number of the current record

       OFMT	    output format for numbers (default %.6g)

       OFS	    output field separator (default blank)

       ORS	    output record separator (default new-line)

       RS	    input record separator (default new-line)

       An action is a sequence of statements. A statement can be one of the following:

	 if ( expression ) statement [ else statement ]
	 while ( expression ) statement
	 do statement while ( expression )
	 for ( expression ; expression ; expression ) statement
	 for ( var in array ) statement
	 break
	 continue
	 { [ statement ] ... }
	 expression	 # commonly variable = expression
	 print [ expression-list ] [ >expression ]
	 printf format [ ,expression-list ] [ >expression ]
	 next		 # skip remaining patterns on this input line
	 exit [expr]	 # skip the rest of the input; exit status is expr

       Statements are terminated by semicolons, newlines, or right braces. An  empty  expression-
       list  stands  for  the  whole  input line. Expressions take on string or numeric values as
       appropriate, and are built using the operators +, -, *, /, %, ^ and  concatenation  (indi-
       cated by a blank). The operators ++, --, +=, -=, *=, /=, %=, ^=, >, >=, <, <=, ==, !=, and
       ?: are also available in expressions. Variables can be scalars,	array  elements  (denoted
       x[i]),  or  fields. Variables are initialized to the null string or zero. Array subscripts
       can be any string, not necessarily numeric; this allows for a form of associative  memory.
       String constants are quoted (""), with the usual C escapes recognized within.

       The  print statement prints its arguments on the standard output, or on a file if >expres-
       sion is present, or on a pipe if '|cmd' is present. The output  resulted  from  the  print
       statement is terminated by the output record separator with each argument separated by the
       current output field separator. The printf statement formats its expression list according
       to the format (see printf(3C)).

   Built-in Functions
       The arithmetic functions are as follows:

       cos(x)	  Return  cosine  of  x,  where  x is in radians. (In /usr/xpg4/bin/awk only. See
		  nawk(1).)

       sin(x)	  Return sine of x, where x  is  in  radians.  (In  /usr/xpg4/bin/awk  only.  See
		  nawk(1).)

       exp(x)	  Return the exponential function of x.

       log(x)	  Return the natural logarithm of x.

       sqrt(x)	  Return the square root of x.

       int(x)	  Truncate its argument to an integer. It is truncated toward 0 when x > 0.

       The string functions are as follows:

       index(s, t)

	   Return the position in string s where string t first occurs, or 0 if it does not occur
	   at all.

       int(s)

	   truncates s to an integer value. If s is not specified, $0 is used.

       length(s)

	   Return the length of its argument taken as a string, or of the whole line if there  is
	   no argument.

       split(s, a, fs)

	   Split  the string s into array elements a[1], a[2], ... a[n], and returns n. The sepa-
	   ration is done with the regular expression fs or with the field separator FS if fs  is
	   not given.

       sprintf(fmt, expr, expr,...)

	   Format the expressions according to the printf(3C) format given by fmt and returns the
	   resulting string.

       substr(s, m, n)

	   returns the n-character substring of s that begins at position m.

       The input/output function is as follows:

       getline	  Set $0 to the next input record from the current input file. getline returns	1
		  for successful input, 0 for end of file, and -1 for an error.

   Large File Behavior
       See  largefile(5)  for  the  description  of  the  behavior of awk when encountering files
       greater than or equal to 2 Gbyte ( 2^31 bytes).

EXAMPLES
       Example 1 Printing Lines Longer Than 72 Characters

       The following example is an awk script that can be executed by  an  awk	-f  examplescript
       style command. It prints lines longer than seventy two characters:

	 length > 72

       Example 2 Printing Fields in Opposite Order

       The  following  example	is  an awk script that can be executed by an awk -f examplescript
       style command. It prints the first two fields in opposite order:

	 { print $2, $1 }

       Example 3 Printing Fields in Opposite Order with the Input Fields Separated

       The following example is an awk script that can be executed by  an  awk	-f  examplescript
       style  command.	It  prints  the  first two input fields in opposite order, separated by a
       comma, blanks or tabs:

	 BEGIN { FS = ",[ \t]*|[ \t]+" }
	       { print $2, $1 }

       Example 4 Adding Up the First Column, Printing the Sum and Average

       The following example is an awk script that can be executed by  an  awk	-f  examplescript
       style command.  It adds up the first column, and prints the sum and average:

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

       Example 5 Printing Fields in Reverse Order

       The  following  example	is  an awk script that can be executed by an awk -f examplescript
       style command. It prints fields in reverse order:

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

       Example 6 Printing All lines Between start/stop Pairs

       The following example is an awk script that can be executed by  an  awk	-f  examplescript
       style command. It prints all lines between start/stop pairs.

	 /start/, /stop/

       Example 7 Printing All Lines Whose First Field is Different from the Previous One

       The  following  example	is  an awk script that can be executed by an awk -f examplescript
       style command. It prints all lines whose first field is different from the previous one.

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

       Example 8 Printing a File and Filling in Page numbers

       The following example is an awk script that can be executed by  an  awk	-f  examplescript
       style command. It prints a file and fills in page numbers starting at 5:

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

       Example 9 Printing a File and Numbering Its Pages

       Assuming this program is in a file named prog, the following example prints the file input
       numbering its pages starting at 5:

	 example% awk -f prog n=5 input

ENVIRONMENT VARIABLES
       See environ(5) for descriptions of the following environment  variables	that  affect  the
       execution of awk: LANG, LC_ALL, LC_COLLATE, LC_CTYPE, LC_MESSAGES, NLSPATH, and PATH.

       LC_NUMERIC    Determine the radix character used when interpreting numeric input, perform-
		     ing conversions between numeric and string  values  and  formatting  numeric
		     output.  Regardless of locale, the period character (the decimal-point char-
		     acter of the POSIX locale) is the decimal-point character recognized in pro-
		     cessing awk programs (including assignments in command-line arguments).

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

   /usr/bin/awk
       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWesu			   |
       +-----------------------------+-----------------------------+
       |CSI			     |Not Enabled		   |
       +-----------------------------+-----------------------------+

   /usr/xpg4/bin/awk
       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWxcu4			   |
       +-----------------------------+-----------------------------+
       |CSI			     |Enabled			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO
       egrep(1),  grep(1),  nawk(1), sed(1), printf(3C), attributes(5), environ(5), largefile(5),
       standards(5)

NOTES
       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 an expression to be treated as a string,
       concatenate the null string ("") to it.

SunOS 5.11				   22 Jun 2005					   awk(1)


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