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gawk(1)
Free Software Foundation
NAME
gawk - pattern scanning and processing language
SYNOPSIS
gawk [-W gawk-options] [-Ffs] [-v var=val] -fprogram-file [--] file...
gawk [-W gawk-options] [-Ffs] [-v var=val] [--] program-text file...
OPTIONS
Gawk accepts the following options, which should be available on any
implementation of the AWK language.
-Ffs
Use fs for the input field separator (the value of the FS predefined
variable).
-v var=val
Assign the value val, to the variable var, before execution of the
program begins. Such variable values are available to the BEGIN block
of an AWK program.
-f program-file
Read the AWK program source from the file program-file, instead of from
the first command line argument. Multiple -f options may be used.
-- Signal the end of options. This is useful to allow further arguments to
the AWK program itself to start with a "-". This is mainly for
consistency with the argument parsing convention used by most other
POSIX programs.
Following the POSIX standard, gawk-specific options are supplied via
arguments to the -W option. Multiple -W options may be supplied, or
multiple arguments may be supplied together if they are separated by
commas, or enclosed in quotes and separated by white space. Case is ignored
in arguments to the -W option.
The -W option accepts the following arguments:
compat
Run in compatibility mode. In compatibility mode, gawk behaves
identically to UNIX awk; none of the GNU-specific extensions are
recognized. See GNU EXTENSIONS, below, for more information.
copyleft
copyright
Print the short version of the GNU copyright information message on the
error output.
lint
Provide warnings about constructs that are dubious or non-portable to
other AWK implementations.
posix
This turns on compatibility mode, with the following additional
restrictions:
·
\x escape sequences are not recognized.
·
The synonym func for the keyword function is not recognized.
·
The operators ** and **= cannot be used in place of ^ and ^=.
version
Print version information for this particular copy of gawk on the error
output. This is useful mainly for knowing if the current copy of gawk
on your system is up to date with respect to whatever the Free Software
Foundation is distributing.
Any other options are flagged as illegal, but are otherwise ignored.
DESCRIPTION
Gawk is the GNU Project's implementation of the AWK programming language.
It conforms to the definition of the language in the POSIX 1003.2 Command
Language And Utilities Standard (draft 11). This version in turn is based
on the description in The AWK Programming Language, by Aho, Kernighan, and
Weinberger, with the additional features defined in the System V Release 4
version of UNIX awk. Gawk also provides some GNU-specific extensions.
The command line consists of options to gawk itself, the AWK program text
(if not supplied via the -f option), and values to be made available in the
ARGC and ARGV pre-defined AWK variables.
AWK PROGRAM EXECUTION
An AWK program consists of a sequence of pattern-action statements and
optional function definitions.
pattern { action statements }
function name(parameter list) { statements }
Gawk first reads the program source from the program-file(s) if specified,
or from the first non-option argument on the command line. The -f option
may be used multiple times on the command line. Gawk will read the program
text as if all the program-files had been concatenated together. This is
useful for building libraries of AWK functions, without having to include
them in each new AWK program that uses them. To use a library function in
a file from a program typed in on the command line, specify /dev/tty as one
of the program-files, type your program, and end it with a ^D (control-d).
The environment variable AWKPATH specifies a search path to use when
finding source files named with the -f option. If this variable does not
exist, the default path is ".:/usr/lib/awk:/usr/local/lib/awk". If a file
name given to the -f option contains a "/" character, no path search is
performed.
Gawk executes AWK programs in the following order. First, gawk compiles
the program into an internal form. Next, all variable assignments
specified via the -v option are performed. Then, gawk executes the code in
the BEGIN block(s) (if any), and then proceeds to read each file named in
the ARGV array. If there are no files named on the command line, gawk reads
the standard input.
If a filename on the command line has the form var=val it is treated as a
variable assignment. The variable var will be assigned the value val.
(This happens after any BEGIN block(s) have been run.) Command line
variable assignment is most useful for dynamically assigning values to the
variables AWK uses to control how input is broken into fields and records.
It is also useful for controlling state if multiple passes are needed over
a single data file.
If the value of a particular element of ARGV is empty (""), gawk skips over
it.
For each line in the input, gawk tests to see if it matches any pattern in
the AWK program. For each pattern that the line matches, the associated
action is executed. The patterns are tested in the order they occur in the
program.
Finally, after all the input is exhausted, gawk executes the code in the
END block(s) (if any).
VARIABLES AND FIELDS
AWK variables are dynamic; they come into existence when they are first
used. Their values are either floating-point numbers or strings, or both,
depending upon how they are used. AWK also has one dimension arrays;
multiply dimensioned arrays may be simulated. Several pre-defined variables
are set as a program runs; these will be described as needed and summarized
below.
Fields
As each input line is read, gawk splits the line into fields, using the
value of the FS variable as the field separator. If FS is a single
character, fields are separated by that character. Otherwise, FS is
expected to be a full regular expression. In the special case that FS is a
single blank, fields are separated by runs of blanks and/or tabs. Note that
the value of IGNORECASE (see below) will also affect how fields are split
when FS is a regular expression.
If the FIELDWIDTHS variable is set to a space separated list of numbers,
each field is expected to have fixed width, and gawk will split up the
record using the specified widths. The value of FS is ignored. Assigning a
new value to FS overrides the use of FIELDWIDTHS, and restores the default
behavior.
Each field in the input line may be referenced by its position, $1, $2, and
so on. $0 is the whole line. The value of a field may be assigned to as
well. Fields need not be referenced by constants:
n = 5
print $n
prints the fifth field in the input line. The variable NF is set to the
total number of fields in the input line.
References to non-existent fields (i.e. fields after $NF) produce the
null-string. However, assigning to a non-existent field (e.g., $(NF+2) = 5)
will increase the value of NF, create any intervening fields with the null
string as their value, and cause the value of $0 to be recomputed, with the
fields being separated by the value of OFS.
Built-in Variables
AWK's built-in variables are:
ARGC
The number of command line arguments (does not include options to gawk,
or the program source).
ARGV
Array of command line arguments. The array is indexed from 0 to ARGC -
1. Dynamically changing the contents of ARGV can control the files used
for data.
CONVFMT
The conversion format for numbers, "%.6g", by default.
ENVIRON
An array containing the values of the current environment. The array
is indexed by the environment variables, each element being the value
of that variable (e.g., ENVIRON["HOME"] might be /u/arnold). Changing
this array does not affect the environment seen by programs which gawk
spawns via redirection or the system() function. (This may change in a
future version of gawk.)
FIELDWIDTHS
A white-space separated list of fieldwidths. When set, gawk parses the
input into fields of fixed width, instead of using the value of the FS
variable as the field separator. The fixed field width facility is
still experimental; expect the semantics to change as gawk evolves over
time.
FILENAME
The name of the current input file. If no files are specified on the
command line, the value of FILENAME is "-".
FNR The input record number in the current input file.
FS The input field separator, a blank by default.
IGNORECASE
Controls the case-sensitivity of all regular expression operations. If
IGNORECASE has a non-zero value, then pattern matching in rules, field
splitting with FS, regular expression matching with ~ and !~, and the
gsub(), index(), match(), split(), and sub() pre-defined functions will
all ignore case when doing regular expression operations. Thus, if
IGNORECASE is not equal to zero, /aB/ matches all of the strings "ab",
"aB", "Ab", and "AB". As with all AWK variables, the initial value of
IGNORECASE is zero, so all regular expression operations are normally
case-sensitive.
NF The number of fields in the current input record.
NR The total number of input records seen so far.
OFMT
The output format for numbers, "%.6g", by default.
OFS The output field separator, a blank by default.
ORS The output record separator, by default a newline.
RS The input record separator, by default a newline. RS is exceptional in
that only the first character of its string value is used for
separating records. (This will probably change in a future release of
gawk.) If RS is set to the null string, then records are separated by
blank lines. When RS is set to the null string, then the newline
character always acts as a field separator, in addition to whatever
value FS may have.
RSTART
The index of the first character matched by match(); 0 if no match.
RLENGTH
The length of the string matched by match(); -1 if no match.
SUBSEP
The character used to separate multiple subscripts in array elements,
by default "\034".
Arrays
Arrays are subscripted with an expression between square brackets ([ and
]). If the expression is an expression list (expr, expr ...) then the array
subscript is a string consisting of the concatenation of the (string) value
of each expression, separated by the value of the SUBSEP variable. This
facility is used to simulate multiply dimensioned arrays. For example:
i = "A" ; j = "B" ; k = "C"
x[i, j, k] = "hello, world\n"
assigns the string "hello, world\n" to the element of the array x which is
indexed by the string "A\034B\034C". All arrays in AWK are associative,
i.e. indexed by string values.
The special operator in may be used in an if or while statement to see if
an array has an index consisting of a particular value.
if (val in array)
print array[val]
If the array has multiple subscripts, use (i, j) in array.
The in construct may also be used in a for loop to iterate over all the
elements of an array.
An element may be deleted from an array using the delete statement.
Variable Typing And Conversion
Variables and fields may be (floating point) numbers, or strings, or both.
How the value of a variable is interpreted depends upon its context. If
used in a numeric expression, it will be treated as a number, if used as a
string it will be treated as a string.
To force a variable to be treated as a number, add 0 to it; to force it to
be treated as a string, concatenate it with the null string.
When a string must be converted to a number, the conversion is accomplished
using atof(3). A number is converted to a string by using the value of
CONVFMT as a format string for sprintf(3), with the numeric value of the
variable as the argument. However, even though all numbers in AWK are
floating-point, integral values are always converted as integers. Thus,
given
CONVFMT = "%2.2f"
a = 12
b = a ""
the variable b has a value of "12" and not "12.00".
Gawk performs comparisons as follows: If two variables are numeric, they
are compared numerically. If one value is numeric and the other has a
string value that is a "numeric string," then comparisons are also done
numerically. Otherwise, the numeric value is converted to a string and a
string comparison is performed. Two strings are compared, of course, as
strings. According to the POSIX standard (draft 11), even if two strings
are numeric strings, a numeric comparison is performed. However, this is
clearly incorrect, and gawk does not do this.
Uninitialized variables have the numeric value 0 and the string value (the
null, or empty, string).
PATTERNS AND ACTIONS
AWK is a line oriented language. The pattern comes first, and then the
action. Action statements are enclosed in { and }. Either the pattern may
be missing, or the action may be missing, but, of course, not both. If the
pattern is missing, the action will be executed for every single line of
input. A missing action is equivalent to
{ print }
which prints the entire line.
Comments begin with the "#" character, and continue until the end of the
line. Blank lines may be used to separate statements. Normally, a statement
ends with a newline, however, this is not the case for lines ending in a
",", "{", "?", ":", "&&", or "||". Lines ending in do or else also have
their statements automatically continued on the following line. In other
cases, a line can be continued by ending it with a "\", in which case the
newline will be ignored.
Multiple statements may be put on one line by separating them with a ``;''.
This applies to both the statements within the action part of a pattern-
action pair (the usual case), and to the pattern-action statements
themselves.
Patterns
AWK patterns may be one of the following:
BEGIN
END
/regular expression/
relational expression
pattern && pattern
pattern || pattern
pattern ? pattern : pattern
(pattern)
! pattern
pattern1, pattern2
BEGIN and END are two special kinds of patterns which are not tested
against the input. The action parts of all BEGIN patterns are merged as if
all the statements had been written in a single BEGIN block. They are
executed before any of the input is read. Similarly, all the END blocks are
merged, and executed when all the input is exhausted (or when an exit
statement is executed). BEGIN and END patterns cannot be combined with
other patterns in pattern expressions. BEGIN and END patterns cannot have
missing action parts.
For /regular expression/ patterns, the associated statement is executed for
each input line that matches the regular expression. Regular expressions
are the same as those in egrep(1), and are summarized below.
A relational expression may use any of the operators defined below in the
section on actions. These generally test whether certain fields match
certain regular expressions.
The &&, ||, and ! operators are logical AND, logical OR, and logical NOT,
respectively, as in C. They do short-circuit evaluation, also as in C, and
are used for combining more primitive pattern expressions. As in most
languages, parentheses may be used to change the order of evaluation.
The ?: operator is like the same operator in C. If the first pattern is
true then the pattern used for testing is the second pattern, otherwise it
is the third. Only one of the second and third patterns is evaluated.
The pattern1, pattern2 form of an expression is called a range pattern. It
matches all input records starting with a line that matches pattern1, and
continuing until a record that matches pattern2, inclusive. It does not
combine with any other sort of pattern expression.
Regular Expressions
Regular expressions are the extended kind found in egrep. They are
composed of characters as follows:
c matches the non-metacharacter c.
\c matches the literal character c.
. matches any character except newline.
^ matches the beginning of a line or a string.
$ matches the end of a line or a string.
[abc...]
character class, matches any of the characters abc....
[^abc...]
negated character class, matches any character except abc... and
newline.
r1|r2
alternation: matches either r1 or r2.
r1r2
concatenation: matches r1, and then r2.
r+ matches one or more r's.
r* matches zero or more r's.
r? matches zero or one r's.
(r) grouping: matches r.
The escape sequences that are valid in string constants (see below) are
also legal in regular expressions.
Actions
Action statements are enclosed in braces, { and }. Action statements
consist of the usual assignment, conditional, and looping statements found
in most languages. The operators, control statements, and input/output
statements available are patterned after those in C.
Operators
The operators in AWK, in order of increasing precedence, are
= += -=
*= /= %= ^=
Assignment. Both absolute assignment (var = value) and operator-
assignment (the other forms) are supported.
?: The C conditional expression. This has the form expr1 ? expr2 : expr3.
If expr1 is true, the value of the expression is expr2, otherwise it is
expr3. Only one of expr2 and expr3 is evaluated.
|| Logical OR.
&& Logical AND.
~ !~
Regular expression match, negated match.
Note
Do not use a constant regular expression (/foo/) on the left-hand
side of a ~ or !~. Only use one on the right-hand side. The
expression /foo/ ~ exp has the same meaning as (($0 ~ /foo/) ~ exp).
This is usually not what was intended.
< >
<= >=
!= ==
The regular relational operators.
blank
String concatenation.
+ - Addition and subtraction.
* / %
Multiplication, division, and modulus.
+ - !
Unary plus, unary minus, and logical negation.
^ Exponentiation (** may also be used, and **= for the assignment
operator).
++ --
Increment and decrement, both prefix and postfix.
$ Field reference.
Control Statements
The control statements are as follows:
if (condition) statement [ else statement ]
while (condition) statement
do statement while (condition)
for (expr1; expr2; expr3) statement
for (var in array) statement
break
continue
delete array[index]
exit [ expression ]
{ statements }
I/O Statements
The input/output statements are as follows:
close(filename)
Close file (or pipe, see below).
getline
Set $0 from next input record; set NF, NR, FNR.
getline <file
Set $0 from next record of file; set NF.
getline var
Set var from next input record; set NF, FNR.
getline var <file
Set var from next record of file.
next
Stop processing the current input record. The next input record is read
and processing starts over with the first pattern in the AWK program.
If the end of the input data is reached, the END block(s), if any, are
executed.
next file
Stop processing the current input file. The next input record read
comes from the next input file. FILENAME is updated, FNR is reset to
1, and processing starts over with the first pattern in the AWK
program. If the end of the input data is reached, the END block(s), if
any, are executed.
print
Prints the current record.
print expr-list
Prints expressions.
print expr-list >file
Prints expressions on file.
printf fmt, expr-list
Format and print.
printf fmt, expr-list >file
Format and print on file.
system(cmd-line)
Execute the command cmd-line, and return the exit status. (This may not
be available on non-POSIX systems.)
Other input/output redirections are also allowed. For print and printf,
>>file appends output to the file, while | command writes on a pipe. In a
similar fashion, command | getline pipes into getline. Getline will return
0 on end of file, and -1 on an error.
The printf Statement
The AWK versions of the printf statement and sprintf() function (see below)
accept the following conversion specification formats:
%c An ASCII character. If the argument used for %c is numeric, it is
treated as a character and printed. Otherwise, the argument is assumed
to be a string, and the only first character of that string is printed.
%d A decimal number (the integer part).
%i Just like %d.
%e A floating point number of the form [-]d.ddddddE[+ -]dd.
%f A floating point number of the form [-]ddd.dddddd.
%g Use e or f conversion, whichever is shorter, with nonsignificant zeros
suppressed.
%o An unsigned octal number (again, an integer).
%s A character string.
%x An unsigned hexadecimal number (an integer).
%X Like %x, but using ABCDEF instead of abcdef.
%% A single % character; no argument is converted.
There are optional, additional parameters that may lie between the % and
the control letter:
- The expression should be left-justified within its field.
width
The field should be padded to this width. If the number has a leading
zero, then the field will be padded with zeros. Otherwise it is padded
with blanks.
.prec
A number indicating the maximum width of strings or digits to the right
of the decimal point.
The dynamic width and prec capabilities of the ANSI C printf() routines are
supported. A * in place of either the width or prec specifications will
cause their values to be taken from the argument list to printf or
sprintf().
Special File Names
When doing I/O redirection from either print or printf into a file, or via
getline from a file, gawk recognizes certain special filenames internally.
These filenames allow access to open file descriptors inherited from gawk's
parent process (usually the shell). The filenames are:
/dev/stdin
The standard input.
/dev/stdout
The standard output.
/dev/stderr
The standard error output.
/dev/fd/n
The file associated with the open file descriptor n.
These are particularly useful for error messages. For example:
print "You blew it!" > "/dev/stderr"
whereas you would otherwise have to use
print "You blew it!" | "cat 1>&2"
These file names may also be used on the command line to name data files.
Numeric Functions
AWK has the following pre-defined arithmetic functions:
atan2(y, x)
returns the arctangent of y/x in radians.
cos(expr)
returns the cosine in radians.
exp(expr)
the exponential function.
int(expr)
truncates to integer.
log(expr)
the natural logarithm function.
rand()
returns a random number between 0 and 1.
sin(expr)
returns the sine in radians.
sqrt(expr)
the square root function.
srand(expr)
use expr as a new seed for the random number generator. If no expr is
provided, the time of day will be used. The return value is the
previous seed for the random number generator.
String Functions
AWK has the following pre-defined string functions:
gsub(r, s, t)
for each substring matching the regular expression r in the string t,
substitute the string s, and return the number of substitutions. If t
is not supplied, use $0.
index(s, t)
returns the index of the string t in the string s, or 0 if t is not
present.
length(s)
returns the length of the string s, or the length of $0 if s is not
supplied.
match(s, r)
returns the position in s where the regular expression r occurs, or 0
if r is not present, and sets the values of RSTART and RLENGTH.
split(s, a, r)
splits the string s into the array a on the regular expression r, and
returns the number of fields. If r is omitted, FS is used instead.
sprintf(fmt, expr-list)
prints expr-list according to fmt, and returns the resulting string.
sub(r, s, t)
just like gsub(), but only the first matching substring is replaced.
substr(s, i, n)
returns the n-character substring of s starting at i. If n is omitted,
the rest of s is used.
tolower(str)
returns a copy of the string str, with all the upper-case characters in
str translated to their corresponding lower-case counterparts. Non-
alphabetic characters are left unchanged.
toupper(str)
returns a copy of the string str, with all the lower-case characters in
str translated to their corresponding upper-case counterparts. Non-
alphabetic characters are left unchanged.
Time Functions
Since one of the primary uses of AWK programs is processing log files that
contain time stamp information, gawk provides the following two functions
for obtaining time stamps and formatting them.
systime()
returns the current time of day as the number of seconds since the
Epoch (Midnight UTC, January 1, 1970 on POSIX systems).
strftime(format, timestamp)
formats timestamp according to the specification in format. The
timestamp should be of the same form as returned by systime(). If
timestamp is missing, the current time of day is used. See the
specification for the strftime() function in ANSI C for the format
conversions that are guaranteed to be available. A public-domain
version of strftime(3) and a man page for it are shipped with gawk; if
that version was used to build gawk, then all of the conversions
described in that man page are available to gawk.
String Constants
String constants in AWK are sequences of characters enclosed between double
quotes ("). Within strings, certain escape sequences are recognized, as in
C. These are:
\\ A literal backslash.
\a The "alert" character; usually the ASCII BEL character.
\b backspace.
\f form-feed.
\n new line.
\r carriage return.
\t horizontal tab.
\v vertical tab.
\xhex digits
The character represented by the string of hexadecimal digits following
the \x. As in ANSI C, all following hexadecimal digits are considered
part of the escape sequence. (This feature should tell us something
about language design by committee.) E.g., "\x1B" is the ASCII ESC
(escape) character.
\ddd
The character represented by the 1-, 2-, or 3-digit sequence of octal
digits. E.g. "\033" is the ASCII ESC (escape) character.
\c The literal character c.
The escape sequences may also be used inside constant regular expressions
(e.g., /[ \t\f\n\r\v]/ matches whitespace characters).
FUNCTIONS
Functions in AWK are defined as follows:
function name(parameter list) { statements }
Functions are executed when called from within the action parts of regular
pattern-action statements. Actual parameters supplied in the function call
are used to instantiate the formal parameters declared in the function.
Arrays are passed by reference, other variables are passed by value.
Since functions were not originally part of the AWK language, the provision
for local variables is rather clumsy: They are declared as extra parameters
in the parameter list. The convention is to separate local variables from
real parameters by extra spaces in the parameter list. For example:
function f(p, q, a, b) { # a & b are local
..... }
/abc/ { ... ; f(1, 2) ; ... }
The left parenthesis in a function call is required to immediately follow
the function name, without any intervening white space. This is to avoid a
syntactic ambiguity with the concatenation operator. This restriction does
not apply to the built-in functions listed above.
Functions may call each other and may be recursive. Function parameters
used as local variables are initialized to the null string and the number
zero upon function invocation.
The word func may be used in place of function.
EXAMPLES
Print and sort the login names of all users:
BEGIN { FS = ":" }
{ print $1 | "sort" }
Count lines in a file:
{ nlines++ }
END { print nlines }
Precede each line by its number in the file:
{ print FNR, $0 }
Concatenate and line number (a variation on a theme):
{ print NR, $0 }
POSIX COMPATIBILITY
A primary goal for gawk is compatibility with the POSIX standard, as well
as with the latest version of UNIX awk. To this end, gawk incorporates the
following user visible features which are not described in the AWK book,
but are part of awk in System V Release 4, and are in the POSIX standard.
The -v option for assigning variables before program execution starts is
new. The book indicates that command line variable assignment happens when
awk would otherwise open the argument as a file, which is after the BEGIN
block is executed. However, in earlier implementations, when such an
assignment appeared before any file names, the assignment would happen
before the BEGIN block was run. Applications came to depend on this
"feature." When awk was changed to match its documentation, this option was
added to accommodate applications that depended upon the old behavior.
(This feature was agreed upon by both the AT&T and GNU developers.)
The -W option for implementation specific features is from the POSIX
standard.
When processing arguments, gawk uses the special option "--" to signal the
end of arguments, and warns about, but otherwise ignores, undefined
options.
The AWK book does not define the return value of srand(). The System V
Release 4 version of UNIX awk (and the POSIX standard) has it return the
seed it was using, to allow keeping track of random number sequences.
Therefore srand() in gawk also returns its current seed.
Other new features are: The use of multiple -f options (from MKS awk); the
ENVIRON array; the \a, and \v escape sequences (done originally in gawk and
fed back into AT&T's); the tolower() and toupper() built-in functions (from
AT&T); and the ANSI C conversion specifications in printf (done first in
AT&T's version).
GNU EXTENSIONS
Gawk has some extensions to POSIX awk. They are described in this section.
All the extensions described here can be disabled by invoking gawk with the
-W compat option.
The following features of gawk are not available in POSIX awk.
· The \x escape sequence.
· The systime() and strftime() functions.
· The special file names available for I/O redirection are not
recognized.
· The IGNORECASE variable and its side-effects are not available.
· The FIELDWIDTHS variable and fixed width field splitting.
· No path search is performed for files named via the -f option.
Therefore the AWKPATH environment variable is not special.
· The use of next file to abandon processing of the current input file.
The AWK book does not define the return value of the close() function.
Gawk's close() returns the value from fclose(3), or pclose(3), when closing
a file or pipe, respectively.
When gawk is invoked with the -W compat option, if the fs argument to the
-F option is "t", then FS will be set to the tab character. Since this is a
rather ugly special case, it is not the default behavior. This behavior
also does not occur if -Wposix has been specified.
HISTORICAL FEATURES
There are two features of historical AWK implementations that gawk
supports. First, it is possible to call the length() built-in function not
only with no argument, but even without parentheses! Thus,
a = length
is the same as either of
a = length()
a = length($0)
This feature is marked as "deprecated" in the POSIX standard, and gawk will
issue a warning about its use if -Wlint is specified on the command line.
The other feature is the use of the continue statement outside the body of
a while, for, or do loop. Traditional AWK implementations have treated
such usage as equivalent to the next statement. Gawk will support this
usage if -Wposix has not been specified.
The -F option is not necessary given the command line variable assignment
feature; it remains only for backwards compatibility.
VERSION INFORMATION
This man page documents gawk, version 2.14.
For the 2.14 version of gawk, the -c, -V, -C, -a, and -e options of the
2.11 version are recognized. However, gawk will print a warning message,
and these options will go away in the 2.15 version.
SEE ALSO
egrep(1)
The AWK Programming Language, Alfred V. Aho, Brian W. Kernighan, Peter J.
Weinberger, Addison-Wesley, 1988. ISBN 0-201-07981-X.
Programming Support Tools
AUTHORS
The original version of UNIX awk was designed and implemented by Alfred
Aho, Peter Weinberger, and Brian Kernighan of AT&T Bell Labs. Brian
Kernighan continues to maintain and enhance it.
Paul Rubin and Jay Fenlason, of the Free Software Foundation, wrote gawk,
to be compatible with the original version of awk distributed in Seventh
Edition UNIX. John Woods contributed a number of bug fixes. David Trueman,
with contributions from Arnold Robbins, made gawk compatible with the new
version of UNIX awk.
The initial DOS port was done by Conrad Kwok and Scott Garfinkle. Scott
Deifik is the current DOS maintainer. Pat Rankin did the port to VMS, and
Michal Jaegermann did the port to the Atari ST.
ACKNOWLEDGEMENTS
Brian Kernighan of Bell Labs provided valuable assistance during testing
and debugging. We thank him.