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-.\"
-.\" Sun Microsystems, Inc. gratefully acknowledges The Open Group for
-.\" permission to reproduce portions of its copyrighted documentation.
-.\" Original documentation from The Open Group can be obtained online at
-.\" http://www.opengroup.org/bookstore/.
-.\"
-.\" The Institute of Electrical and Electronics Engineers and The Open
-.\" Group, have given us permission to reprint portions of their
-.\" documentation.
-.\"
-.\" In the following statement, the phrase ``this text'' refers to portions
-.\" of the system documentation.
-.\"
-.\" Portions of this text are reprinted and reproduced in electronic form
-.\" in the SunOS Reference Manual, from IEEE Std 1003.1, 2004 Edition,
-.\" Standard for Information Technology -- Portable Operating System
-.\" Interface (POSIX), The Open Group Base Specifications Issue 6,
-.\" Copyright (C) 2001-2004 by the Institute of Electrical and Electronics
-.\" Engineers, Inc and The Open Group. In the event of any discrepancy
-.\" between these versions and the original IEEE and The Open Group
-.\" Standard, the original IEEE and The Open Group Standard is the referee
-.\" document. The original Standard can be obtained online at
-.\" http://www.opengroup.org/unix/online.html.
-.\"
-.\" This notice shall appear on any product containing this material.
-.\"
-.\" The contents of this file are subject to the terms of the
-.\" Common Development and Distribution License (the "License").
-.\" You may not use this file except in compliance with the License.
-.\"
-.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
-.\" or http://www.opensolaris.org/os/licensing.
-.\" See the License for the specific language governing permissions
-.\" and limitations under the License.
-.\"
-.\" When distributing Covered Code, include this CDDL HEADER in each
-.\" file and include the License file at usr/src/OPENSOLARIS.LICENSE.
-.\" If applicable, add the following below this CDDL HEADER, with the
-.\" fields enclosed by brackets "[]" replaced with your own identifying
-.\" information: Portions Copyright [yyyy] [name of copyright owner]
-.\"
-.\"
-.\" Copyright 1989 AT&T
-.\" Copyright 1992, X/Open Company Limited All Rights Reserved
-.\" Portions Copyright (c) 2005, 2006 Sun Microsystems, Inc. All Rights Reserved
-.\" Copyright 2018, Joyent, Inc.
-.\"
-.TH NAWK 1 "Nov 9, 2018"
-.SH NAME
-nawk \- pattern scanning and processing language
-.SH SYNOPSIS
-.LP
-.nf
-\fB/usr/bin/nawk\fR [\fB-F\fR \fIERE\fR] [\fB-v\fR \fIassignment\fR] \fI\&'program'\fR | \fB-f\fR \fIprogfile\fR...
- [\fIargument\fR]...
-.fi
-
-.LP
-.nf
-\fB/usr/xpg4/bin/awk\fR [\fB-F\fR \fIERE\fR] [\fB-v\fR \fIassignment\fR]... \fI\&'program'\fR | \fB-f\fR \fIprogfile\fR...
- [\fIargument\fR]...
-.fi
-
-.SH DESCRIPTION
-.LP
-The \fB/usr/bin/nawk\fR and \fB/usr/xpg4/bin/awk\fR utilities execute
-\fIprogram\fRs written in the \fBnawk\fR programming language, which is
-specialized for textual data manipulation. A \fBnawk\fR \fIprogram\fR is a
-sequence of patterns and corresponding actions. The string specifying
-\fIprogram\fR must be enclosed in single quotes (') to protect it from
-interpretation by the shell. The sequence of pattern - action statements can be
-specified in the command line as \fIprogram\fR or in one, or more, file(s)
-specified by the \fB-f\fR\fIprogfile\fR option. When input is read that matches
-a pattern, the action associated with the pattern is performed.
-.sp
-.LP
-Input is interpreted as a sequence of records. By default, a record is a line,
-but this can be changed by using the \fBRS\fR built-in variable. Each record of
-input is matched to each pattern in the \fIprogram\fR. For each pattern
-matched, the associated action is executed.
-.sp
-.LP
-The \fBnawk\fR utility interprets each input record as a sequence of fields
-where, by default, a field is a string of non-blank characters. This default
-white-space field delimiter (blanks and/or tabs) can be changed by using the
-\fBFS\fR built-in variable or the \fB-F\fR\fIERE\fR option. The \fBnawk\fR
-utility denotes the first field in a record \fB$1\fR, the second \fB$2\fR, and
-so forth. The symbol \fB$0\fR refers to the entire record; setting any other
-field causes the reevaluation of \fB$0\fR. Assigning to \fB$0\fR resets the
-values of all fields and the \fBNF\fR built-in variable.
-
-.SH OPTIONS
-.LP
-The following options are supported:
-.sp
-.ne 2
-.na
-\fB\fB-F\fR \fIERE\fR\fR
-.ad
-.RS 17n
-Define the input field separator to be the extended regular expression
-\fIERE\fR, before any input is read (can be a character).
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fB-f\fR \fIprogfile\fR\fR
-.ad
-.RS 17n
-Specifies the pathname of the file \fIprogfile\fR containing a \fBnawk\fR
-program. If multiple instances of this option are specified, the concatenation
-of the files specified as \fIprogfile\fR in the order specified is the
-\fBnawk\fR program. The \fBnawk\fR program can alternatively be specified in
-the command line as a single argument.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fB-v\fR \fIassignment\fR\fR
-.ad
-.RS 17n
-The \fIassignment\fR argument must be in the same form as an \fIassignment\fR
-operand. The assignment is of the form \fIvar=value\fR, where \fIvar\fR is the
-name of one of the variables described below. The specified assignment occurs
-before executing the \fBnawk\fR program, including the actions associated with
-\fBBEGIN\fR patterns (if any). Multiple occurrences of this option can be
-specified.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fB-safe\fR\fR
-.ad
-.RS 17n
-When passed to \fBnawk\fR, this flag will prevent the program from opening new
-files or running child processes. The \fBENVIRON\fR array will also not be
-initialized.
-.RE
-
-.SH OPERANDS
-.LP
-The following operands are supported:
-.sp
-.ne 2
-.na
-\fB\fIprogram\fR\fR
-.ad
-.RS 12n
-If no \fB-f\fR option is specified, the first operand to \fBnawk\fR is the text
-of the \fBnawk\fR program. The application supplies the \fIprogram\fR operand
-as a single argument to \fBnawk.\fR If the text does not end in a newline
-character, \fBnawk\fR interprets the text as if it did.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fIargument\fR\fR
-.ad
-.RS 12n
-Either of the following two types of \fIargument\fR can be intermixed:
-.sp
-.ne 2
-.na
-\fB\fIfile\fR\fR
-.ad
-.RS 14n
-A pathname of a file that contains the input to be read, which is matched
-against the set of patterns in the program. If no \fIfile\fR operands are
-specified, or if a \fIfile\fR operand is \fB\(mi\fR, the standard input is
-used.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fIassignment\fR\fR
-.ad
-.RS 14n
-An operand that begins with an underscore or alphabetic character from the
-portable character set, followed by a sequence of underscores, digits and
-alphabetics from the portable character set, followed by the \fB=\fR character
-specifies a variable assignment rather than a pathname. The characters before
-the \fB=\fR represent the name of a \fBnawk\fR variable. If that name is a
-\fBnawk\fR reserved word, the behavior is undefined. The characters following
-the equal sign is interpreted as if they appeared in the \fBnawk\fR program
-preceded and followed by a double-quote (\fB"\fR) character, as a \fBSTRING\fR
-token , except that if the last character is an unescaped backslash, it is
-interpreted as a literal backslash rather than as the first character of the
-sequence \fB\e\fR\&.. The variable is assigned the value of that \fBSTRING\fR
-token. If the value is considered a \fInumeric\fRstring\fI,\fR the variable is
-assigned its numeric value. Each such variable assignment is performed just
-before the processing of the following \fIfile\fR, if any. Thus, an assignment
-before the first \fBfile\fR argument is executed after the \fBBEGIN\fR actions
-(if any), while an assignment after the last \fIfile\fR argument is executed
-before the \fBEND\fR actions (if any). If there are no \fIfile\fR arguments,
-assignments are executed before processing the standard input.
-.RE
-
-.RE
-
-.SH INPUT FILES
-.LP
-Input files to the \fBnawk\fR program from any of the following sources:
-.RS +4
-.TP
-.ie t \(bu
-.el o
-any \fIfile\fR operands or their equivalents, achieved by modifying the
-\fBnawk\fR variables \fBARGV\fR and \fBARGC\fR
-.RE
-.RS +4
-.TP
-.ie t \(bu
-.el o
-standard input in the absence of any \fIfile\fR operands
-.RE
-.RS +4
-.TP
-.ie t \(bu
-.el o
-arguments to the \fBgetline\fR function
-.RE
-.sp
-.LP
-must be text files. Whether the variable \fBRS\fR is set to a value other than
-a newline character or not, for these files, implementations support records
-terminated with the specified separator up to \fB{LINE_MAX}\fR bytes and can
-support longer records.
-.sp
-.LP
-If \fB-\fR\fBf\fR \fIprogfile\fR is specified, the files named by each of the
-\fIprogfile\fR option-arguments must be text files containing an \fBnawk\fR
-program.
-.sp
-.LP
-The standard input are used only if no \fIfile\fR operands are specified, or if
-a \fIfile\fR operand is \fB\(mi\fR\&.
-
-.SH EXTENDED DESCRIPTION
-.LP
-A \fBnawk\fR program is composed of pairs of the form:
-.sp
-.in +2
-.nf
-pattern { \fIaction\fR }
-.fi
-.in -2
-
-.sp
-.LP
-Either the pattern or the action (including the enclosing brace characters) can
-be omitted. Pattern-action statements are separated by a semicolon or by a
-newline.
-.sp
-.LP
-A missing pattern matches any record of input, and a missing action is
-equivalent to an action that writes the matched record of input to standard
-output.
-.sp
-.LP
-Execution of the \fBnawk\fR program starts by first executing the actions
-associated with all \fBBEGIN\fR patterns in the order they occur in the
-program. Then each \fIfile\fR operand (or standard input if no files were
-specified) is processed by reading data from the file until a record separator
-is seen (a newline character by default), splitting the current record into
-fields using the current value of \fBFS\fR, evaluating each pattern in the
-program in the order of occurrence, and executing the action associated with
-each pattern that matches the current record. The action for a matching pattern
-is executed before evaluating subsequent patterns. Last, the actions associated
-with all \fBEND\fR patterns is executed in the order they occur in the program.
-
-.SS "Expressions in nawk"
-.LP
-Expressions describe computations used in \fIpatterns\fR and \fIactions\fR. In
-the following table, valid expression operations are given in groups from
-highest precedence first to lowest precedence last, with equal-precedence
-operators grouped between horizontal lines. In expression evaluation, where the
-grammar is formally ambiguous, higher precedence operators are evaluated before
-lower precedence operators. In this table \fIexpr,\fR \fIexpr1,\fR
-\fIexpr2,\fR and \fIexpr3\fR represent any expression, while \fIlvalue\fR
-represents any entity that can be assigned to (that is, on the left side of an
-assignment operator).
-.sp
-
-.sp
-.TS
-c c c c
-l l l l .
-\fBSyntax\fR \fBName\fR \fBType of Result\fR \fBAssociativity\fR
-_
-( \fIexpr\fR ) Grouping type of \fIexpr\fR n/a
-_
-$\fIexpr\fR Field reference string n/a
-_
-++ \fIlvalue\fR Pre-increment numeric n/a
-\(mi\(mi \fIlvalue\fR Pre-decrement numeric n/a
-\fIlvalue\fR ++ Post-increment numeric n/a
-\fIlvalue\fR \(mi\(mi Post-decrement numeric n/a
-_
-\fIexpr\fR ^ \fIexpr\fR Exponentiation numeric right
-_
-! \fIexpr\fR Logical not numeric n/a
-+ \fIexpr\fR Unary plus numeric n/a
-\(mi \fIexpr\fR Unary minus numeric n/a
-_
-\fIexpr\fR * \fIexpr\fR Multiplication numeric left
-\fIexpr\fR / \fIexpr\fR Division numeric left
-\fIexpr\fR % \fIexpr\fR Modulus numeric left
-_
-\fIexpr\fR + \fIexpr\fR Addition numeric left
-\fIexpr\fR \(mi \fIexpr\fR Subtraction numeric left
-_
-\fIexpr\fR \fIexpr\fR String concatenation string left
-_
-\fIexpr\fR < \fIexpr\fR Less than numeric none
-\fIexpr\fR <= \fIexpr\fR Less than or equal to numeric none
-\fIexpr\fR != \fIexpr\fR Not equal to numeric none
-\fIexpr\fR == \fIexpr\fR Equal to numeric none
-\fIexpr\fR > \fIexpr\fR Greater than numeric none
-\fIexpr\fR >= \fIexpr\fR Greater than or equal to numeric none
-_
-\fIexpr\fR ~ \fIexpr\fR ERE match numeric none
-\fIexpr\fR !~ \fIexpr\fR ERE non-match numeric none
-_
-\fIexpr\fR in array Array membership numeric left
-( \fIindex\fR ) in Multi-dimension array numeric left
- \fIarray\fR membership
-_
-\fBexpr\fR && \fIexpr\fR Logical AND numeric left
-_
-\fBexpr\fR |\|| \fIexpr\fR Logical OR numeric left
-_
-\fIexpr1\fR ? \fIexpr2\fR Conditional expression type of selected right
- : \fIexpr3\fR \fIexpr2\fR or \fIexpr3\fR
-_
-\fIlvalue\fR ^= \fIexpr\fR Exponentiation numeric right
- assignment
-\fIlvalue\fR %= \fIexpr\fR Modulus assignment numeric right
-\fIlvalue\fR *= \fIexpr\fR Multiplication numeric right
- assignment
-\fIlvalue\fR /= \fIexpr\fR Division assignment numeric right
-\fIlvalue\fR += \fIexpr\fR Addition assignment numeric right
-\fIlvalue\fR \(mi= \fIexpr\fR Subtraction assignment numeric right
-\fIlvalue\fR = \fIexpr\fR Assignment type of \fIexpr\fR right
-.TE
-
-.sp
-.LP
-Each expression has either a string value, a numeric value or both. Except as
-stated for specific contexts, the value of an expression is implicitly
-converted to the type needed for the context in which it is used. A string
-value is converted to a numeric value by the equivalent of the following calls:
-.sp
-.in +2
-.nf
-setlocale(LC_NUMERIC, "");
-\fInumeric_value\fR = atof(\fIstring_value\fR);
-.fi
-.in -2
-
-.sp
-.LP
-A numeric value that is exactly equal to the value of an integer is converted
-to a string by the equivalent of a call to the \fBsprintf\fR function with the
-string \fB%d\fR as the \fBfmt\fR argument and the numeric value being converted
-as the first and only \fIexpr\fR argument. Any other numeric value is
-converted to a string by the equivalent of a call to the \fBsprintf\fR function
-with the value of the variable \fBCONVFMT\fR as the \fBfmt\fR argument and the
-numeric value being converted as the first and only \fIexpr\fR argument.
-.sp
-.LP
-A string value is considered to be a \fInumeric string\fR in the following
-case:
-.RS +4
-.TP
-1.
-Any leading and trailing blank characters is ignored.
-.RE
-.RS +4
-.TP
-2.
-If the first unignored character is a \fB+\fR or \fB\(mi\fR, it is ignored.
-.RE
-.RS +4
-.TP
-3.
-If the remaining unignored characters would be lexically recognized as a
-\fBNUMBER\fR token, the string is considered a \fInumeric string\fR.
-.RE
-.sp
-.LP
-If a \fB\(mi\fR character is ignored in the above steps, the numeric value of
-the \fInumeric string\fR is the negation of the numeric value of the recognized
-\fBNUMBER\fR token. Otherwise the numeric value of the \fInumeric string\fR is
-the numeric value of the recognized \fBNUMBER\fR token. Whether or not a string
-is a \fInumeric string\fR is relevant only in contexts where that term is used
-in this section.
-.sp
-.LP
-When an expression is used in a Boolean context, if it has a numeric value, a
-value of zero is treated as false and any other value is treated as true.
-Otherwise, a string value of the null string is treated as false and any other
-value is treated as true. A Boolean context is one of the following:
-.RS +4
-.TP
-.ie t \(bu
-.el o
-the first subexpression of a conditional expression.
-.RE
-.RS +4
-.TP
-.ie t \(bu
-.el o
-an expression operated on by logical NOT, logical \fBAND,\fR or logical OR.
-.RE
-.RS +4
-.TP
-.ie t \(bu
-.el o
-the second expression of a \fBfor\fR statement.
-.RE
-.RS +4
-.TP
-.ie t \(bu
-.el o
-the expression of an \fBif\fR statement.
-.RE
-.RS +4
-.TP
-.ie t \(bu
-.el o
-the expression of the \fBwhile\fR clause in either a \fBwhile\fR or \fBdo\fR
-\fB\&.\|.\|.\fR \fBwhile\fR statement.
-.RE
-.RS +4
-.TP
-.ie t \(bu
-.el o
-an expression used as a pattern (as in Overall Program Structure).
-.RE
-.sp
-.LP
-The \fBnawk\fR language supplies arrays that are used for storing numbers or
-strings. Arrays need not be declared. They are initially empty, and their sizes
-changes dynamically. The subscripts, or element identifiers, are strings,
-providing a type of associative array capability. An array name followed by a
-subscript within square brackets can be used as an \fIlvalue\fR and as an
-expression, as described in the grammar. Unsubscripted array names are used in
-only the following contexts:
-.RS +4
-.TP
-.ie t \(bu
-.el o
-a parameter in a function definition or function call.
-.RE
-.RS +4
-.TP
-.ie t \(bu
-.el o
-the \fBNAME\fR token following any use of the keyword \fBin\fR.
-.RE
-.sp
-.LP
-A valid array \fIindex\fR consists of one or more comma-separated expressions,
-similar to the way in which multi-dimensional arrays are indexed in some
-programming languages. Because \fBnawk\fR arrays are really one-dimensional,
-such a comma-separated list is converted to a single string by concatenating
-the string values of the separate expressions, each separated from the other by
-the value of the \fBSUBSEP\fR variable.
-.sp
-.LP
-Thus, the following two index operations are equivalent:
-.sp
-.in +2
-.nf
-var[expr1, expr2, ... exprn]
-var[expr1 SUBSEP expr2 SUBSEP ... SUBSEP exprn]
-.fi
-.in -2
-
-.sp
-.LP
-A multi-dimensioned \fIindex\fR used with the \fBin\fR operator must be put in
-parentheses. The \fBin\fR operator, which tests for the existence of a
-particular array element, does not create the element if it does not exist.
-Any other reference to a non-existent array element automatically creates it.
-
-.SS "Variables and Special Variables"
-.LP
-Variables can be used in an \fBnawk\fR program by referencing them. With the
-exception of function parameters, they are not explicitly declared.
-Uninitialized scalar variables and array elements have both a numeric value of
-zero and a string value of the empty string.
-.sp
-.LP
-Field variables are designated by a \fB$\fR followed by a number or numerical
-expression. The effect of the field number \fIexpression\fR evaluating to
-anything other than a non-negative integer is unspecified. Uninitialized
-variables or string values need not be converted to numeric values in this
-context. New field variables are created by assigning a value to them.
-References to non-existent fields (that is, fields after \fB$NF\fR) produce the
-null string. However, assigning to a non-existent field (for example,
-\fB$(NF+2) = 5\fR) increases the value of \fBNF\fR, create any intervening
-fields with the null string as their values and cause the value of \fB$0\fR to
-be recomputed, with the fields being separated by the value of \fBOFS\fR. Each
-field variable has a string value when created. If the string, with any
-occurrence of the decimal-point character from the current locale changed to a
-period character, is considered a \fInumeric string\fR (see \fBExpressions in
-nawk\fR above), the field variable also has the numeric value of the \fInumeric
-string\fR.
-
-.SS "/usr/bin/nawk, /usr/xpg4/bin/awk"
-.LP
-\fBnawk\fR sets the following special variables that are supported by both
-\fB/usr/bin/nawk\fR and \fB/usr/xpg4/bin/awk\fR:
-.sp
-.ne 2
-.na
-\fB\fBARGC\fR\fR
-.ad
-.RS 12n
-The number of elements in the \fBARGV\fR array.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBARGV\fR\fR
-.ad
-.RS 12n
-An array of command line arguments, excluding options and the \fIprogram\fR
-argument, numbered from zero to \fBARGC\fR\(mi1.
-.sp
-The arguments in \fBARGV\fR can be modified or added to; \fBARGC\fR can be
-altered. As each input file ends, \fBnawk\fR treats the next non-null element
-of \fBARGV\fR, up to the current value of \fBARGC\fR\(mi1, inclusive, as the
-name of the next input file. Setting an element of \fBARGV\fR to null means
-that it is not treated as an input file. The name \fB\(mi\fR indicates the
-standard input. If an argument matches the format of an \fIassignment\fR
-operand, this argument is treated as an assignment rather than a \fIfile\fR
-argument.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBCONVFMT\fR\fR
-.ad
-.RS 12n
-The \fBprintf\fR format for converting numbers to strings (except for output
-statements, where \fBOFMT\fR is used). The default is \fB%.6g\fR.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBENVIRON\fR\fR
-.ad
-.RS 12n
-The variable \fBENVIRON\fR is an array representing the value of the
-environment. The indices of the array are strings consisting of the names of
-the environment variables, and the value of each array element is a string
-consisting of the value of that variable. If the value of an environment
-variable is considered a \fInumeric string\fR, the array element also has its
-numeric value.
-.sp
-In all cases where \fBnawk\fR behavior is affected by environment variables
-(including the environment of any commands that \fBnawk\fR executes via the
-\fBsystem\fR function or via pipeline redirections with the \fBprint\fR
-statement, the \fBprintf\fR statement, or the \fBgetline\fR function), the
-environment used is the environment at the time \fBnawk\fR began executing.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBFILENAME\fR\fR
-.ad
-.RS 12n
-A pathname of the current input file. Inside a \fBBEGIN\fR action the value is
-undefined. Inside an \fBEND\fR action the value is the name of the last input
-file processed.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBFNR\fR\fR
-.ad
-.RS 12n
-The ordinal number of the current record in the current file. Inside a
-\fBBEGIN\fR action the value is zero. Inside an \fBEND\fR action the value is
-the number of the last record processed in the last file processed.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBFS\fR\fR
-.ad
-.RS 12n
-Input field separator regular expression; a space character by default.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBNF\fR\fR
-.ad
-.RS 12n
-The number of fields in the current record. Inside a \fBBEGIN\fR action, the
-use of \fBNF\fR is undefined unless a \fBgetline\fR function without a
-\fIvar\fR argument is executed previously. Inside an \fBEND\fR action, \fBNF\fR
-retains the value it had for the last record read, unless a subsequent,
-redirected, \fBgetline\fR function without a \fIvar\fR argument is performed
-prior to entering the \fBEND\fR action.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBNR\fR\fR
-.ad
-.RS 12n
-The ordinal number of the current record from the start of input. Inside a
-\fBBEGIN\fR action the value is zero. Inside an \fBEND\fR action the value is
-the number of the last record processed.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBOFMT\fR\fR
-.ad
-.RS 12n
-The \fBprintf\fR format for converting numbers to strings in output statements
-\fB"%.6g"\fR by default. The result of the conversion is unspecified if the
-value of \fBOFMT\fR is not a floating-point format specification.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBOFS\fR\fR
-.ad
-.RS 12n
-The \fBprint\fR statement output field separator; a space character by default.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBORS\fR\fR
-.ad
-.RS 12n
-The \fBprint\fR output record separator; a newline character by default.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBRLENGTH\fR\fR
-.ad
-.RS 12n
-The length of the string matched by the \fBmatch\fR function.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBRS\fR\fR
-.ad
-.RS 12n
-The first character of the string value of \fBRS\fR is the input record
-separator; a newline character by default. If \fBRS\fR contains more than one
-character, the results are unspecified. If \fBRS\fR is null, then records are
-separated by sequences of one or more blank lines. Leading or trailing blank
-lines do not produce empty records at the beginning or end of input, and the
-field separator is always newline, no matter what the value of \fBFS\fR.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBRSTART\fR\fR
-.ad
-.RS 12n
-The starting position of the string matched by the \fBmatch\fR function,
-numbering from 1. This is always equivalent to the return value of the
-\fBmatch\fR function.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBSUBSEP\fR\fR
-.ad
-.RS 12n
-The subscript separator string for multi-dimensional arrays. The default value
-is \fB\e034\fR\&.
-.RE
-
-.SS "/usr/bin/nawk"
-.LP
-The following variable is supported for \fB/usr/bin/nawk\fR only:
-.sp
-.ne 2
-.na
-\fB\fBRT\fR\fR
-.ad
-.RS 12n
-The record terminator for the most recent record read. For most records this
-will be the same value as \fBRS\fR. At the end of a file with no trailing
-separator value, though, this will be set to the empty string (\fB""\fR).
-.RE
-
-.SS "Regular Expressions"
-.LP
-The \fBnawk\fR utility makes use of the extended regular expression notation
-(see \fBregex\fR(5)) except that it allows the use of C-language conventions to
-escape special characters within the EREs, namely \fB\e\e\fR, \fB\ea\fR,
-\fB\eb\fR, \fB\ef\fR, \fB\en\fR, \fB\er\fR, \fB\et\fR, \fB\ev\fR, and those
-specified in the following table. These escape sequences are recognized both
-inside and outside bracket expressions. Note that records need not be
-separated by newline characters and string constants can contain newline
-characters, so even the \fB\en\fR sequence is valid in \fBnawk\fR EREs. Using
-a slash character within the regular expression requires escaping as shown in
-the table below:
-.sp
-
-.sp
-.TS
-l l l
-l l l .
-\fBEscape Sequence\fR \fBDescription\fR \fBMeaning\fR
-_
-\fB\e"\fR Backslash quotation-mark Quotation-mark character
-_
-\fB\e/\fR Backslash slash Slash character
-_
-\fB\e\fR\fIddd\fR T{
-A backslash character followed by the longest sequence of one, two, or three octal-digit characters (01234567). If all of the digits are 0, (that is, representation of the NULL character), the behavior is undefined.
-T} T{
-The character encoded by the one-, two- or three-digit octal integer. Multi-byte characters require multiple, concatenated escape sequences, including the leading \e for each byte.
-T}
-_
-\fB\e\fR\fIc\fR T{
-A backslash character followed by any character not described in this table or special characters (\fB\e\e\fR, \fB\ea\fR, \fB\eb\fR, \fB\ef\fR, \fB\en\fR, \fB\er\fR, \fB\et\fR, \fB\ev\fR).
-T} Undefined
-.TE
-
-.sp
-.LP
-A regular expression can be matched against a specific field or string by using
-one of the two regular expression matching operators, \fB~\fR and \fB!\|~\fR.
-These operators interpret their right-hand operand as a regular expression and
-their left-hand operand as a string. If the regular expression matches the
-string, the \fB~\fR expression evaluates to the value \fB1\fR, and the
-\fB!\|~\fR expression evaluates to the value \fB0\fR. If the regular expression
-does not match the string, the \fB~\fR expression evaluates to the value
-\fB0\fR, and the \fB!\|~\fR expression evaluates to the value \fB1\fR. If the
-right-hand operand is any expression other than the lexical token \fBERE\fR,
-the string value of the expression is interpreted as an extended regular
-expression, including the escape conventions described above. Notice that these
-same escape conventions also are applied in the determining the value of a
-string literal (the lexical token \fBSTRING\fR), and is applied a second time
-when a string literal is used in this context.
-.sp
-.LP
-When an \fBERE\fR token appears as an expression in any context other than as
-the right-hand of the \fB~\fR or \fB!\|~\fR operator or as one of the built-in
-function arguments described below, the value of the resulting expression is
-the equivalent of:
-.sp
-.in +2
-.nf
-$0 ~ /\fIere\fR/
-.fi
-.in -2
-
-.sp
-.LP
-The \fIere\fR argument to the \fBgsub,\fR \fBmatch,\fR \fBsub\fR functions, and
-the \fIfs\fR argument to the \fBsplit\fR function (see \fBString Functions\fR)
-is interpreted as extended regular expressions. These can be either \fBERE\fR
-tokens or arbitrary expressions, and are interpreted in the same manner as the
-right-hand side of the \fB~\fR or \fB!\|~\fR operator.
-.sp
-.LP
-An extended regular expression can be used to separate fields by using the
-\fB-F\fR \fIERE\fR option or by assigning a string containing the expression to
-the built-in variable \fBFS\fR. The default value of the \fBFS\fR variable is a
-single space character. The following describes \fBFS\fR behavior:
-.RS +4
-.TP
-1.
-If \fBFS\fR is a single character:
-.RS +4
-.TP
-.ie t \(bu
-.el o
-If \fBFS\fR is the space character, skip leading and trailing blank characters;
-fields are delimited by sets of one or more blank characters.
-.RE
-.RS +4
-.TP
-.ie t \(bu
-.el o
-Otherwise, if \fBFS\fR is any other character \fIc\fR, fields are delimited by
-each single occurrence of \fIc\fR.
-.RE
-.RE
-.RS +4
-.TP
-2.
-Otherwise, the string value of \fBFS\fR is considered to be an extended
-regular expression. Each occurrence of a sequence matching the extended regular
-expression delimits fields.
-.RE
-.sp
-.LP
-Except in the \fBgsub\fR, \fBmatch\fR, \fBsplit\fR, and \fBsub\fR built-in
-functions, regular expression matching is based on input records. That is,
-record separator characters (the first character of the value of the variable
-\fBRS\fR, a newline character by default) cannot be embedded in the expression,
-and no expression matches the record separator character. If the record
-separator is not a newline character, newline characters embedded in the
-expression can be matched. In those four built-in functions, regular expression
-matching are based on text strings. So, any character (including the newline
-character and the record separator) can be embedded in the pattern and an
-appropriate pattern matches any character. However, in all \fBnawk\fR regular
-expression matching, the use of one or more NULL characters in the pattern,
-input record or text string produces undefined results.
-
-.SS "Patterns"
-.LP
-A \fIpattern\fR is any valid \fIexpression,\fR a range specified by two
-expressions separated by comma, or one of the two special patterns \fBBEGIN\fR
-or \fBEND\fR.
-
-.SS "Special Patterns"
-.LP
-The \fBnawk\fR utility recognizes two special patterns, \fBBEGIN\fR and
-\fBEND\fR. Each \fBBEGIN\fR pattern is matched once and its associated action
-executed before the first record of input is read (except possibly by use of
-the \fBgetline\fR function in a prior \fBBEGIN\fR action) and before command
-line assignment is done. Each \fBEND\fR pattern is matched once and its
-associated action executed after the last record of input has been read. These
-two patterns have associated actions.
-.sp
-.LP
-\fBBEGIN\fR and \fBEND\fR do not combine with other patterns. Multiple
-\fBBEGIN\fR and \fBEND\fR patterns are allowed. The actions associated with the
-\fBBEGIN\fR patterns are executed in the order specified in the program, as are
-the \fBEND\fR actions. An \fBEND\fR pattern can precede a \fBBEGIN\fR pattern
-in a program.
-.sp
-.LP
-If an \fBnawk\fR program consists of only actions with the pattern \fBBEGIN\fR,
-and the \fBBEGIN\fR action contains no \fBgetline\fR function, \fBnawk\fR exits
-without reading its input when the last statement in the last \fBBEGIN\fR
-action is executed. If an \fBnawk\fR program consists of only actions with the
-pattern \fBEND\fR or only actions with the patterns \fBBEGIN\fR and \fBEND\fR,
-the input is read before the statements in the \fBEND\fR actions are executed.
-
-.SS "Expression Patterns"
-.LP
-An expression pattern is evaluated as if it were an expression in a Boolean
-context. If the result is true, the pattern is considered to match, and the
-associated action (if any) is executed. If the result is false, the action is
-not executed.
-
-.SS "Pattern Ranges"
-.LP
-A pattern range consists of two expressions separated by a comma. In this case,
-the action is performed for all records between a match of the first expression
-and the following match of the second expression, inclusive. At this point, the
-pattern range can be repeated starting at input records subsequent to the end
-of the matched range.
-
-.SS "Actions"
-.LP
-An action is a sequence of statements. A statement can be one of the following:
-.sp
-.in +2
-.nf
-if ( \fIexpression\fR ) \fIstatement\fR [ else \fIstatement\fR ]
-while ( \fIexpression\fR ) \fIstatement\fR
-do \fIstatement\fR while ( \fIexpression\fR )
-for ( \fIexpression\fR ; \fIexpression\fR ; \fIexpression\fR ) \fIstatement\fR
-for ( \fIvar\fR in \fIarray\fR ) \fIstatement\fR
-delete \fIarray\fR[\fIsubscript\fR] #delete an array element
-delete \fIarray\fR #delete all elements within an array
-break
-continue
-{ [ \fIstatement\fR ] .\|.\|. }
-\fIexpression\fR # commonly variable = expression
-print [ \fIexpression-list\fR ] [ >\fIexpression\fR ]
-printf format [ ,\fIexpression-list\fR ] [ >\fIexpression\fR ]
-next # skip remaining patterns on this input line
-nextfile # skip remaining patterns on this input file
-exit [expr] # skip the rest of the input; exit status is expr
-return [expr]
-.fi
-.in -2
-
-.sp
-.LP
-Any single statement can be replaced by a statement list enclosed in braces.
-The statements are terminated by newline characters or semicolons, and are
-executed sequentially in the order that they appear.
-.sp
-.LP
-The \fBnext\fR statement causes all further processing of the current input
-record to be abandoned. The behavior is undefined if a \fBnext\fR statement
-appears or is invoked in a \fBBEGIN\fR or \fBEND\fR action.
-.sp
-.LP
-The \fBnextfile\fR statement is similar to \fBnext\fR, but also skips all other
-records in the current file, and moves on to processing the next input file if
-available (or exits the program if there are none). (Note that this keyword is
-not supported by \fB/usr/xpg4/bin/awk\fR.)
-.sp
-.LP
-The \fBexit\fR statement invokes all \fBEND\fR actions in the order in which
-they occur in the program source and then terminate the program without reading
-further input. An \fBexit\fR statement inside an \fBEND\fR action terminates
-the program without further execution of \fBEND\fR actions. If an expression
-is specified in an \fBexit\fR statement, its numeric value is the exit status
-of \fBnawk\fR, unless subsequent errors are encountered or a subsequent
-\fBexit\fR statement with an expression is executed.
-
-.SS "Output Statements"
-.LP
-Both \fBprint\fR and \fBprintf\fR statements write to standard output by
-default. The output is written to the location specified by
-\fIoutput_redirection\fR if one is supplied, as follows:
-.sp
-.in +2
-.nf
-\fB>\fR \fIexpression\fR\fB>>\fR \fIexpression\fR\fB|\fR \fIexpression\fR
-.fi
-.in -2
-
-.sp
-.LP
-In all cases, the \fIexpression\fR is evaluated to produce a string that is
-used as a full pathname to write into (for \fB>\fR or \fB>>\fR) or as a command
-to be executed (for \fB|\fR). Using the first two forms, if the file of that
-name is not currently open, it is opened, creating it if necessary and using
-the first form, truncating the file. The output then is appended to the file.
-As long as the file remains open, subsequent calls in which \fIexpression\fR
-evaluates to the same string value simply appends output to the file. The file
-remains open until the \fBclose\fR function, which is called with an expression
-that evaluates to the same string value.
-.sp
-.LP
-The third form writes output onto a stream piped to the input of a command. The
-stream is created if no stream is currently open with the value of
-\fIexpression\fR as its command name. The stream created is equivalent to one
-created by a call to the \fBpopen\fR(3C) function with the value of
-\fIexpression\fR as the \fIcommand\fR argument and a value of \fBw\fR as the
-\fImode\fR argument. As long as the stream remains open, subsequent calls in
-which \fIexpression\fR evaluates to the same string value writes output to the
-existing stream. The stream remains open until the \fBclose\fR function is
-called with an expression that evaluates to the same string value. At that
-time, the stream is closed as if by a call to the \fBpclose\fR function.
-.sp
-.LP
-These output statements take a comma-separated list of \fIexpression\fR \fIs\fR
-referred in the grammar by the non-terminal symbols \fBexpr_list,\fR
-\fBprint_expr_list\fR or \fBprint_expr_list_opt.\fR This list is referred to
-here as the \fIexpression list\fR, and each member is referred to as an
-\fIexpression argument\fR.
-.sp
-.LP
-The \fBprint\fR statement writes the value of each expression argument onto the
-indicated output stream separated by the current output field separator (see
-variable \fBOFS\fR above), and terminated by the output record separator (see
-variable \fBORS\fR above). All expression arguments is taken as strings, being
-converted if necessary; with the exception that the \fBprintf\fR format in
-\fBOFMT\fR is used instead of the value in \fBCONVFMT\fR. An empty expression
-list stands for the whole input record \fB(\fR$0\fB)\fR.
-.sp
-.LP
-The \fBprintf\fR statement produces output based on a notation similar to the
-File Format Notation used to describe file formats in this document Output is
-produced as specified with the first expression argument as the string
-\fBformat\fR and subsequent expression arguments as the strings \fBarg1\fR to
-\fBargn,\fR inclusive, with the following exceptions:
-.RS +4
-.TP
-1.
-The \fIformat\fR is an actual character string rather than a graphical
-representation. Therefore, it cannot contain empty character positions. The
-space character in the \fIformat\fR string, in any context other than a
-\fIflag\fR of a conversion specification, is treated as an ordinary character
-that is copied to the output.
-.RE
-.RS +4
-.TP
-2.
-If the character set contains a Delta character and that character appears
-in the \fIformat\fR string, it is treated as an ordinary character that is
-copied to the output.
-.RE
-.RS +4
-.TP
-3.
-The \fIescape sequences\fR beginning with a backslash character is treated
-as sequences of ordinary characters that are copied to the output. Note that
-these same sequences is interpreted lexically by \fBnawk\fR when they appear in
-literal strings, but they is not treated specially by the \fBprintf\fR
-statement.
-.RE
-.RS +4
-.TP
-4.
-A \fIfield width\fR or \fIprecision\fR can be specified as the \fB*\fR
-character instead of a digit string. In this case the next argument from the
-expression list is fetched and its numeric value taken as the field width or
-precision.
-.RE
-.RS +4
-.TP
-5.
-The implementation does not precede or follow output from the \fBd\fR or
-\fBu\fR conversion specifications with blank characters not specified by the
-\fIformat\fR string.
-.RE
-.RS +4
-.TP
-6.
-The implementation does not precede output from the \fBo\fR conversion
-specification with leading zeros not specified by the \fIformat\fR string.
-.RE
-.RS +4
-.TP
-7.
-For the \fBc\fR conversion specification: if the argument has a numeric
-value, the character whose encoding is that value is output. If the value is
-zero or is not the encoding of any character in the character set, the behavior
-is undefined. If the argument does not have a numeric value, the first
-character of the string value is output; if the string does not contain any
-characters the behavior is undefined.
-.RE
-.RS +4
-.TP
-8.
-For each conversion specification that consumes an argument, the next
-expression argument is evaluated. With the exception of the \fBc\fR conversion,
-the value is converted to the appropriate type for the conversion
-specification.
-.RE
-.RS +4
-.TP
-9.
-If there are insufficient expression arguments to satisfy all the conversion
-specifications in the \fIformat\fR string, the behavior is undefined.
-.RE
-.RS +4
-.TP
-10.
-If any character sequence in the \fIformat\fR string begins with a %
-character, but does not form a valid conversion specification, the behavior is
-unspecified.
-.RE
-.sp
-.LP
-Both \fBprint\fR and \fBprintf\fR can output at least \fB{LINE_MAX}\fR bytes.
-
-.SS "Functions"
-.LP
-The \fBnawk\fR language has a variety of built-in functions: arithmetic,
-string, input/output and general.
-
-.SS "Arithmetic Functions"
-.LP
-The arithmetic functions, except for \fBint\fR, are based on the \fBISO\fR
-\fBC\fR standard. The behavior is undefined in cases where the \fBISO\fR
-\fBC\fR standard specifies that an error be returned or that the behavior is
-undefined. Although the grammar permits built-in functions to appear with no
-arguments or parentheses, unless the argument or parentheses are indicated as
-optional in the following list (by displaying them within the \fB[ ]\fR
-brackets), such use is undefined.
-.sp
-.ne 2
-.na
-\fB\fBatan2(\fR\fIy\fR,\fIx\fR\fB)\fR\fR
-.ad
-.RS 17n
-Return arctangent of \fIy\fR/\fIx\fR.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBcos\fR(\fIx\fR)\fR
-.ad
-.RS 17n
-Return cosine of \fIx,\fR where \fIx\fR is in radians.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBsin\fR(\fIx\fR)\fR
-.ad
-.RS 17n
-Return sine of \fIx,\fR where \fIx\fR is in radians.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBexp\fR(\fIx\fR)\fR
-.ad
-.RS 17n
-Return the exponential function of \fIx\fR.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBlog\fR(\fIx\fR)\fR
-.ad
-.RS 17n
-Return the natural logarithm of \fIx\fR.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBsqrt\fR(\fIx\fR)\fR
-.ad
-.RS 17n
-Return the square root of \fIx\fR.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBint\fR(\fIx\fR)\fR
-.ad
-.RS 17n
-Truncate its argument to an integer. It is truncated toward 0 when \fIx\fR > 0.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBrand()\fR\fR
-.ad
-.RS 17n
-Return a random number \fIn\fR, such that 0 \(<= \fIn\fR < 1.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBsrand\fR([\fBexpr\fR])\fR
-.ad
-.RS 17n
-Set the seed value for \fBrand\fR to \fIexpr\fR or use the time of day if
-\fIexpr\fR is omitted. The previous seed value is returned.
-.RE
-
-.SS "String Functions"
-.LP
-The string functions in the following list shall be supported. Although the
-grammar permits built-in functions to appear with no arguments or parentheses,
-unless the argument or parentheses are indicated as optional in the following
-list (by displaying them within the \fB[ ]\fR brackets), such use is undefined.
-.sp
-.ne 2
-.na
-\fB\fBgsub\fR(\fIere\fR,\fIrepl\fR[,\|\fIin\fR])\fR
-.ad
-.sp .6
-.RS 4n
-Behave like \fBsub\fR (see below), except that it replaces all occurrences of
-the regular expression (like the \fBed\fR utility global substitute) in
-\fB$0\fR or in the \fIin\fR argument, when specified.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBindex\fR(\fIs\fR,\fIt\fR)\fR
-.ad
-.sp .6
-.RS 4n
-Return the position, in characters, numbering from 1, in string \fIs\fR where
-string \fIt\fR first occurs, or zero if it does not occur at all.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBlength\fR[([\fIv\fR])]\fR
-.ad
-.sp .6
-.RS 4n
-Given no argument, this function returns the length of the whole record,
-\fB$0\fR. If given an array as an argument (and using \fB/usr/bin/nawk\fR),
-then this returns the number of elements it contains. Otherwise, this function
-interprets the argument as a string (performing any needed conversions) and
-returns its length in characters.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBmatch\fR(\fIs\fR,\fIere\fR)\fR
-.ad
-.sp .6
-.RS 4n
-Return the position, in characters, numbering from 1, in string \fIs\fR where
-the extended regular expression \fIere\fR occurs, or zero if it does not occur
-at all. \fBRSTART\fR is set to the starting position (which is the same as the
-returned value), zero if no match is found; \fBRLENGTH\fR is set to the length
-of the matched string, \(mi1 if no match is found.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBsplit\fR(\fIs\fR,\fIa\fR[,\|\fIfs\fR])\fR
-.ad
-.sp .6
-.RS 4n
-Split the string \fIs\fR into array elements \fIa\fR[1], \fIa\fR[2],
-\fB\&...,\fR \fIa\fR[\fIn\fR], and return \fIn\fR. The separation is done with
-the extended regular expression \fIfs\fR or with the field separator \fBFS\fR
-if \fIfs\fR is not given. Each array element has a string value when created.
-If the string assigned to any array element, with any occurrence of the
-decimal-point character from the current locale changed to a period character,
-would be considered a \fInumeric string\fR; the array element also has the
-numeric value of the \fInumeric string\fR. The effect of a null string as the
-value of \fIfs\fR is unspecified.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBsprintf\fR(\fBfmt\fR,\fIexpr\fR,\fIexpr\fR,\fB\&...\fR)\fR
-.ad
-.sp .6
-.RS 4n
-Format the expressions according to the \fBprintf\fR format given by \fIfmt\fR
-and return the resulting string.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBsub\fR(\fIere\fR,\fIrepl\fR[,\|\fIin\fR])\fR
-.ad
-.sp .6
-.RS 4n
-Substitute the string \fIrepl\fR in place of the first instance of the extended
-regular expression \fBERE\fR in string in and return the number of
-substitutions. An ampersand ( \fB&\fR ) appearing in the string \fIrepl\fR is
-replaced by the string from in that matches the regular expression. An
-ampersand preceded with a backslash ( \fB\e\fR ) is interpreted as the literal
-ampersand character. An occurrence of two consecutive backslashes is
-interpreted as just a single literal backslash character. Any other occurrence
-of a backslash (for example, preceding any other character) is treated as a
-literal backslash character. If \fIrepl\fR is a string literal, the handling of
-the ampersand character occurs after any lexical processing, including any
-lexical backslash escape sequence processing. If \fBin\fR is specified and it
-is not an \fBlvalue\fR the behavior is undefined. If in is omitted, \fBnawk\fR
-uses the current record (\fB$0\fR) in its place.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBsubstr\fR(\fIs\fR,\fIm\fR[,\|\fIn\fR])\fR
-.ad
-.sp .6
-.RS 4n
-Return the at most \fIn\fR-character substring of \fIs\fR that begins at
-position \fIm,\fR numbering from 1. If \fIn\fR is missing, the length of the
-substring is limited by the length of the string \fIs\fR.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBtolower\fR(\fIs\fR)\fR
-.ad
-.sp .6
-.RS 4n
-Return a string based on the string \fIs\fR. Each character in \fIs\fR that is
-an upper-case letter specified to have a \fBtolower\fR mapping by the
-\fBLC_CTYPE\fR category of the current locale is replaced in the returned
-string by the lower-case letter specified by the mapping. Other characters in
-\fIs\fR are unchanged in the returned string.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBtoupper\fR(\fIs\fR)\fR
-.ad
-.sp .6
-.RS 4n
-Return a string based on the string \fIs\fR. Each character in \fIs\fR that is
-a lower-case letter specified to have a \fBtoupper\fR mapping by the
-\fBLC_CTYPE\fR category of the current locale is replaced in the returned
-string by the upper-case letter specified by the mapping. Other characters in
-\fIs\fR are unchanged in the returned string.
-.RE
-
-.sp
-.LP
-All of the preceding functions that take \fIERE\fR as a parameter expect a
-pattern or a string valued expression that is a regular expression as defined
-below.
-
-.SS "Input/Output and General Functions"
-.LP
-The input/output and general functions are:
-.sp
-.ne 2
-.na
-\fB\fBclose(\fR\fIexpression\fR)\fR
-.ad
-.RS 27n
-Close the file or pipe opened by a \fBprint\fR or \fBprintf\fR statement or a
-call to \fBgetline\fR with the same string-valued \fIexpression\fR. If the
-close was successful, the function returns \fB0\fR; otherwise, it returns
-non-zero.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBfflush(\fR\fIexpression\fR)\fR
-.ad
-.RS 27n
-Flush any buffered output for the file or pipe opened by a \fBprint\fR or
-\fBprintf\fR statement or a call to \fBgetline\fR with the same string-valued
-\fIexpression\fR. If the flush was successful, the function returns \fB0\fR;
-otherwise, it returns \fBEOF\fR. If no arguments or the empty string
-(\fB""\fR) are given, then all open files will be flushed. (Note that
-\fBfflush\fR is supported in \fB/usr/bin/nawk\fR only.)
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fIexpression\fR|\fBgetline\fR[\fIvar\fR]\fR
-.ad
-.RS 27n
-Read a record of input from a stream piped from the output of a command. The
-stream is created if no stream is currently open with the value of
-\fIexpression\fR as its command name. The stream created is equivalent to one
-created by a call to the \fBpopen\fR function with the value of
-\fIexpression\fR as the \fIcommand\fR argument and a value of \fBr\fR as the
-\fImode\fR argument. As long as the stream remains open, subsequent calls in
-which \fIexpression\fR evaluates to the same string value reads subsequent
-records from the file. The stream remains open until the \fBclose\fR function
-is called with an expression that evaluates to the same string value. At that
-time, the stream is closed as if by a call to the \fBpclose\fR function. If
-\fIvar\fR is missing, \fB$0\fR and \fBNF\fR is set. Otherwise, \fIvar\fR is
-set.
-.sp
-The \fBgetline\fR operator can form ambiguous constructs when there are
-operators that are not in parentheses (including concatenate) to the left of
-the \fB|\fR (to the beginning of the expression containing \fBgetline\fR). In
-the context of the \fB$\fR operator, \fB|\fR behaves as if it had a lower
-precedence than \fB$\fR. The result of evaluating other operators is
-unspecified, and all such uses of portable applications must be put in
-parentheses properly.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBgetline\fR\fR
-.ad
-.RS 27n
-Set \fB$0\fR to the next input record from the current input file. This form of
-\fBgetline\fR sets the \fBNF\fR, \fBNR\fR, and \fBFNR\fR variables.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBgetline\fR \fIvar\fR\fR
-.ad
-.RS 27n
-Set variable \fIvar\fR to the next input record from the current input file.
-This form of \fBgetline\fR sets the \fBFNR\fR and \fBNR\fR variables.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBgetline\fR [\fIvar\fR] \fB<\fR \fIexpression\fR\fR
-.ad
-.RS 27n
-Read the next record of input from a named file. The \fIexpression\fR is
-evaluated to produce a string that is used as a full pathname. If the file of
-that name is not currently open, it is opened. As long as the stream remains
-open, subsequent calls in which \fIexpression\fR evaluates to the same string
-value reads subsequent records from the file. The file remains open until the
-\fBclose\fR function is called with an expression that evaluates to the same
-string value. If \fIvar\fR is missing, \fB$0\fR and \fBNF\fR is set. Otherwise,
-\fIvar\fR is set.
-.sp
-The \fBgetline\fR operator can form ambiguous constructs when there are binary
-operators that are not in parentheses (including concatenate) to the right of
-the \fB<\fR (up to the end of the expression containing the \fBgetline\fR). The
-result of evaluating such a construct is unspecified, and all such uses of
-portable applications must be put in parentheses properly.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fBsystem\fR(\fIexpression\fR)\fR
-.ad
-.RS 27n
-Execute the command given by \fIexpression\fR in a manner equivalent to the
-\fBsystem\fR(3C) function and return the exit status of the command.
-.RE
-
-.sp
-.LP
-All forms of \fBgetline\fR return \fB1\fR for successful input, \fB0\fR for end
-of file, and \fB\(mi1\fR for an error.
-.sp
-.LP
-Where strings are used as the name of a file or pipeline, the strings must be
-textually identical. The terminology ``same string value'' implies that
-``equivalent strings'', even those that differ only by space characters,
-represent different files.
-
-.SS "User-defined Functions"
-.LP
-The \fBnawk\fR language also provides user-defined functions. Such functions
-can be defined as:
-.sp
-.in +2
-.nf
-\fBfunction\fR \fIname\fR(\fIargs\fR,\|.\|.\|.) { \fIstatements\fR }
-.fi
-.in -2
-
-.sp
-.LP
-A function can be referred to anywhere in an \fBnawk\fR program; in particular,
-its use can precede its definition. The scope of a function is global.
-.sp
-.LP
-Function arguments can be either scalars or arrays; the behavior is undefined
-if an array name is passed as an argument that the function uses as a scalar,
-or if a scalar expression is passed as an argument that the function uses as an
-array. Function arguments are passed by value if scalar and by reference if
-array name. Argument names are local to the function; all other variable names
-are global. The same name is not used as both an argument name and as the name
-of a function or a special \fBnawk\fR variable. The same name must not be used
-both as a variable name with global scope and as the name of a function. The
-same name must not be used within the same scope both as a scalar variable and
-as an array.
-.sp
-.LP
-The number of parameters in the function definition need not match the number
-of parameters in the function call. Excess formal parameters can be used as
-local variables. If fewer arguments are supplied in a function call than are in
-the function definition, the extra parameters that are used in the function
-body as scalars are initialized with a string value of the null string and a
-numeric value of zero, and the extra parameters that are used in the function
-body as arrays are initialized as empty arrays. If more arguments are supplied
-in a function call than are in the function definition, the behavior is
-undefined.
-.sp
-.LP
-When invoking a function, no white space can be placed between the function
-name and the opening parenthesis. Function calls can be nested and recursive
-calls can be made upon functions. Upon return from any nested or recursive
-function call, the values of all of the calling function's parameters are
-unchanged, except for array parameters passed by reference. The \fBreturn\fR
-statement can be used to return a value. If a \fBreturn\fR statement appears
-outside of a function definition, the behavior is undefined.
-.sp
-.LP
-In the function definition, newline characters are optional before the opening
-brace and after the closing brace. Function definitions can appear anywhere in
-the program where a \fIpattern-action\fR pair is allowed.
-
-.SH USAGE
-.LP
-The \fBindex\fR, \fBlength\fR, \fBmatch\fR, and \fBsubstr\fR functions should
-not be confused with similar functions in the \fBISO C\fR standard; the
-\fBnawk\fR versions deal with characters, while the \fBISO C\fR standard deals
-with bytes.
-.sp
-.LP
-Because the concatenation operation is represented by adjacent expressions
-rather than an explicit operator, it is often necessary to use parentheses to
-enforce the proper evaluation precedence.
-.sp
-.LP
-See \fBlargefile\fR(5) for the description of the behavior of \fBnawk\fR when
-encountering files greater than or equal to 2 Gbyte (2^31 bytes).
-
-.SH EXAMPLES
-.LP
-The \fBnawk\fR program specified in the command line is most easily specified
-within single-quotes (for example, \fB\&'\fR\fIprogram\fR\fB\&'\fR) for
-applications using \fBsh\fR, because \fBnawk\fR programs commonly contain
-characters that are special to the shell, including double-quotes. In the cases
-where a \fBnawk\fR program contains single-quote characters, it is usually
-easiest to specify most of the program as strings within single-quotes
-concatenated by the shell with quoted single-quote characters. For example:
-.sp
-.in +2
-.nf
-nawk '/'\e''/ { print "quote:", $0 }'
-.fi
-.in -2
-
-.sp
-.LP
-prints all lines from the standard input containing a single-quote character,
-prefixed with \fBquote:\fR.
-.sp
-.LP
-The following are examples of simple \fBnawk\fR programs:
-.LP
-\fBExample 1 \fRWrite to the standard output all input lines for which field 3
-is greater than 5:
-.sp
-.in +2
-.nf
-\fB$3 > 5\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 2 \fRWrite every tenth line:
-.sp
-.in +2
-.nf
-\fB(NR % 10) == 0\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 3 \fRWrite any line with a substring matching the regular
-expression:
-.sp
-.in +2
-.nf
-\fB/(G|D)(2[0-9][[:alpha:]]*)/\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 4 \fRPrint any line with a substring containing a G or D, followed
-by a sequence of digits and characters:
-.sp
-.LP
-This example uses character classes \fBdigit\fR and \fBalpha\fR to match
-language-independent digit and alphabetic characters, respectively.
-
-.sp
-.in +2
-.nf
-\fB/(G|D)([[:digit:][:alpha:]]*)/\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 5 \fRWrite any line in which the second field matches the regular
-expression and the fourth field does not:
-.sp
-.in +2
-.nf
-\fB$2 ~ /xyz/ && $4 !~ /xyz/\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 6 \fRWrite any line in which the second field contains a backslash:
-.sp
-.in +2
-.nf
-\fB$2 ~ /\e\e/\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 7 \fRWrite any line in which the second field contains a backslash
-(alternate method):
-.sp
-.LP
-Notice that backslash escapes are interpreted twice, once in lexical processing
-of the string and once in processing the regular expression.
-
-.sp
-.in +2
-.nf
-\fB$2 ~ "\e\e\e\e"\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 8 \fRWrite the second to the last and the last field in each line,
-separating the fields by a colon:
-.sp
-.in +2
-.nf
-\fB{OFS=":";print $(NF-1), $NF}\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 9 \fRWrite the line number and number of fields in each line:
-.sp
-.LP
-The three strings representing the line number, the colon and the number of
-fields are concatenated and that string is written to standard output.
-
-.sp
-.in +2
-.nf
-\fB{print NR ":" NF}\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 10 \fRWrite lines longer than 72 characters:
-.sp
-.in +2
-.nf
-\fB{length($0) > 72}\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 11 \fRWrite first two fields in opposite order separated by the OFS:
-.sp
-.in +2
-.nf
-\fB{ print $2, $1 }\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 12 \fRSame, with input fields separated by comma or space and tab
-characters, or both:
-.sp
-.in +2
-.nf
-\fBBEGIN { FS = ",[\et]*|[\et]+" }
- { print $2, $1 }\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 13 \fRAdd up first column, print sum and average:
-.sp
-.in +2
-.nf
-\fB{s += $1 }
-END {print "sum is ", s, " average is", s/NR}\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 14 \fRWrite fields in reverse order, one per line (many lines out
-for each line in):
-.sp
-.in +2
-.nf
-\fB{ for (i = NF; i > 0; --i) print $i }\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 15 \fRWrite all lines between occurrences of the strings "start" and
-"stop":
-.sp
-.in +2
-.nf
-\fB/start/, /stop/\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 16 \fRWrite all lines whose first field is different from the
-previous one:
-.sp
-.in +2
-.nf
-\fB$1 != prev { print; prev = $1 }\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 17 \fRSimulate the echo command:
-.sp
-.in +2
-.nf
-\fBBEGIN {
- for (i = 1; i < ARGC; ++i)
- printf "%s%s", ARGV[i], i==ARGC-1?"\en":""
- }\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 18 \fRWrite the path prefixes contained in the PATH environment
-variable, one per line:
-.sp
-.in +2
-.nf
-\fBBEGIN {
- n = split (ENVIRON["PATH"], path, ":")
- for (i = 1; i <= n; ++i)
- print path[i]
- }\fR
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 19 \fRPrint the file "input", filling in page numbers starting at 5:
-.sp
-.LP
-If there is a file named \fBinput\fR containing page headers of the form
-
-.sp
-.in +2
-.nf
-Page#
-.fi
-.in -2
-
-.sp
-.LP
-and a file named \fBprogram\fR that contains
-
-.sp
-.in +2
-.nf
-/Page/{ $2 = n++; }
-{ print }
-.fi
-.in -2
-
-.sp
-.LP
-then the command line
-
-.sp
-.in +2
-.nf
-\fBnawk -f program n=5 input\fR
-.fi
-.in -2
-.sp
-
-.sp
-.LP
-prints the file \fBinput\fR, filling in page numbers starting at 5.
-
-.SH ENVIRONMENT VARIABLES
-.LP
-See \fBenviron\fR(5) for descriptions of the following environment variables
-that affect execution: \fBLC_COLLATE\fR, \fBLC_CTYPE\fR, \fBLC_MESSAGES\fR, and
-\fBNLSPATH\fR.
-.sp
-.ne 2
-.na
-\fB\fBLC_NUMERIC\fR\fR
-.ad
-.RS 14n
-Determine the radix character used when interpreting numeric input, performing
-conversions between numeric and string values and formatting numeric output.
-Regardless of locale, the period character (the decimal-point character of the
-POSIX locale) is the decimal-point character recognized in processing \fBawk\fR
-programs (including assignments in command-line arguments).
-.RE
-
-.SH EXIT STATUS
-.LP
-The following exit values are returned:
-.sp
-.ne 2
-.na
-\fB\fB0\fR\fR
-.ad
-.RS 6n
-All input files were processed successfully.
-.RE
-
-.sp
-.ne 2
-.na
-\fB\fB>0\fR\fR
-.ad
-.RS 6n
-An error occurred.
-.RE
-
-.sp
-.LP
-The exit status can be altered within the program by using an \fBexit\fR
-expression.
-
-.SH SEE ALSO
-.LP
-\fBawk\fR(1), \fBed\fR(1), \fBegrep\fR(1), \fBgrep\fR(1), \fBlex\fR(1),
-\fBsed\fR(1), \fBpopen\fR(3C), \fBprintf\fR(3C), \fBsystem\fR(3C),
-\fBattributes\fR(5), \fBenviron\fR(5), \fBlargefile\fR(5), \fBregex\fR(5),
-\fBXPG4\fR(5)
-.sp
-.LP
-Aho, A. V., B. W. Kernighan, and P. J. Weinberger, \fIThe AWK Programming
-Language\fR, Addison-Wesley, 1988.
-
-.SH DIAGNOSTICS
-.LP
-If any \fIfile\fR operand is specified and the named file cannot be accessed,
-\fBnawk\fR writes a diagnostic message to standard error and terminate without
-any further action.
-.sp
-.LP
-If the program specified by either the \fIprogram\fR operand or a
-\fIprogfile\fR operand is not a valid \fBnawk\fR program (as specified in
-\fBEXTENDED DESCRIPTION\fR), the behavior is undefined.
-
-.SH NOTES
-.LP
-Input white space is not preserved on output if fields are involved.
-.sp
-.LP
-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 (\fB""\fR) to it.