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awk (1)
  • >> awk (1) ( Solaris man: Команды и прикладные программы пользовательского уровня )
  • awk (1) ( FreeBSD man: Команды и прикладные программы пользовательского уровня )
  • awk (1) ( Русские man: Команды и прикладные программы пользовательского уровня )
  • awk (1) ( Linux man: Команды и прикладные программы пользовательского уровня )
  • awk (1) ( POSIX man: Команды и прикладные программы пользовательского уровня )
  • awk (8) ( Русские man: Команды системного администрирования )
  • Ключ awk обнаружен в базе ключевых слов.
  •  

    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 performed 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 discussion 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 ~ (contains) 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 keywords 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 (indicated 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 >expression 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 separation 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, 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 awk programs (including assignments in command-line arguments).

     

    ATTRIBUTES

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

    /usr/bin/awk

    ATTRIBUTE TYPEATTRIBUTE VALUE

    AvailabilitySUNWesu

    CSI

     

    /usr/xpg4/bin/awk

    ATTRIBUTE TYPEATTRIBUTE VALUE

    AvailabilitySUNWxcu4

    CSI

    Interface Stability

     

    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.


     

    Index

    NAME
    SYNOPSIS
    DESCRIPTION
    OPTIONS
    USAGE
    Input Lines
    Pattern-action Statements
    Built-in Variables
    Built-in Functions
    Large File Behavior
    EXAMPLES
    ENVIRONMENT VARIABLES
    ATTRIBUTES
    /usr/bin/awk
    /usr/xpg4/bin/awk
    SEE ALSO
    NOTES


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