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AWKA(1) USER COMMANDS AWKA(1)
NAME
awka - AWK language to ANSI C translator and library
SYNOPSIS
awka [-c fn] [-X] [-x] [-t] [-o filename] [-a args] [-w args] [-I
include-dir] [-i include-file] [-L lib-dir] [-l lib-file] [-f progname]
[-d] [program] [--] [exe-args]
awka [-version] [-help]
DESCRIPTION
Awka is two products - a translator of AWK language programs to ANSI-C,
and a library of essential functions against which the translated code
must be linked.
The AWK language is useful for maniplation of datafiles, text retrieval
and processing, and for prototyping and experimenting with algorithms.
Usually AWK is implemented as an interpretive language - there are
several good free interpreters available, notably gawk, mawk and 'The
One True Awk' maintained by Brian Kernighan.
This manpage does not explain how AWK works - refer to the SEE ALSO
section at the end of this page for references.
Awka is a new awk meaning it implements the AWK language as defined in
Aho, Kernighan and Weinberger, The AWK Programming Language, Addison-
Wesley Publishing 1988. Awka includes features from the Posix 1003.2
(draft 11.3) definition of the AWK language, but does not necessarily
conform in entirety to Posix standards. Awka also provides a number of
extensions not found in other implementations of AWK.
AWKA OPTIONS
-c fn
Instead of producing a 'main' function, awka will instead generate
'fn' as a controlling function. This is useful where the compiled C
code is to be linked in with a larger application. The -c argument
is not compatible with the -X and -x arguments. See the section
USING awka -c below for more details on how to use this option.
-X
awka will generate C code, which will then be compiled into an
executable, using the C compiler and intallation paths defined when
Awka was installed. The C code will be stored in 'awka_out.c' and
the executable in 'awka.out' or 'awka_out.exe'.
-x
The same as -X, except that the compiled program will also be
executed using arguments following the '--' option on the command-
line.
-t
To be used in conjunction with -x. The C file and the executable
will be removed following execution of the program.
-o filename
To be used in conjunction with -x and -X. The generated executable
will be called 'filename' rather than the default 'awka.out'.
-a args
This embeds executable command-line arguments within the translated
code itself. For example, awka -X -a "-We" file.awk will create an
awka.out that will already have -We in its command-line when it is
run. To see what arguments have been embedded in an executable, use
-showarg at runtime.
-w args
Prints various warnings to stderr, useful in debugging large, complex
AWK programs. None of these are errors - all are acceptable uses of
the AWK language. Depending on your programming style, however, they
could be useful in narrowing down where problems may be occuring.
args can contain the following characters:-
a - prints a list of all global variables.
b - warns about variables set to a value but not referenced.
c - warns about variables referenced but not set to a value.
d - reports use of global vars within a function.
e - reports use of global vars within just one function.
f - requires declaration of global variables.
g - warns about assignments used as truth expressions.
NOTE: As at version 0.5.8 only a, b and c are implemented.
-I include-dir
Specifies a directory in which include files required by awka, or
defined by the user, reside. You may use as many -I options as you
like.
-i include-file
Specifies an include filename to be inserted in the translated code.
-L lib-dir
Specifies a directory containing libraries that may be required by
awka, or defined for linking by the user. See the awka-elm manpage
for more details.
-l lib-file
Specifies a library file to be linked to the translated code
generated by awka at compile time (this only really makes sense if
using awka -x). The lib-file is specified in the same way as C
compilers, that is, the library libmystuff.a would be referred to as
"-l mystuff".
Again, see the awka-elm manpage for details on awka extension
libraries. Like the three previous options, you can use this as
often as you like on a commandline.
-f progname
Specifies the name of an AWK language program to be translated to C.
Multiple -f arguments may be specified.
program
An AWK language program on the command-line, usually surrounded by
single quotes (').
--
All arguments following this will be passed to the compiled
executable when it is executed. This argument only makes sense when
-x has been specified.
exe-args
Arguments to be passed directly to the executable when it is run.
-h
Prints a short summary of command-line options.
-v
Prints version information then quits.
EXECUTABLE OPTIONS
An executable formed by compiling Awka-generated code against libawka.a
will also understand several command-line arguments.
-help
Prints a short summary of executable command-line options, then
exits.
-We
Following command-line arguments will be stored in the ARGV array,
and not parsed as options.
-Wi
Sets unbuffered writes to stdout and line buffered reads from stdin.
-v var=value
Sets variable 'var' to 'value'. 'var' must be a defined scalar
variable within the original AWK program else an error message will
be generated.
-F value
Sets FS to value.
-showarg
Displays any embedded command-line arguments, then exits.
-awkaversion
Shows which version of awka generated the .c code for the executable.
ADDITIONAL FEATURES
awka contains a number of builtin functions may or may not presently be
found in standard AWK implementations. The functions have been added
to extend functionality, or to provide a faster method of performing
tasks that AWK could otherwise undertake in an inefficient way.
The new functions are:-
totitle(s)
converts a string to Title or Proper case, with the first letter of
each word uppercased, the remainder lowercased.
abort()
Exits the AWK program immediately without running the END section.
Originally from TAWK, Gawk now supports abort() as well.
alength(a)
returns the number of elements stored in array variable a.
asort(src [,dest])
The function introduced in Gawk 3.1.0. From Gawk's manpage, this
"returns the number of elements in the source array src. The
contents of src are sorted using awka's normal rules for comparing
values, and the indexes of the sorted values of src are replaced with
sequential integers starting with 1. If the optional destination
array dest is specified, then src is first duplicated into dest, and
then dest is sorted, leaving the indexes of the source array src
unchanged."
ascii(s,n)
Returns the ascii value of character n in string s. If n is omitted,
the value of the first character will be returned. If n is longer
than the string, the last character will be returned. A Null string
will result in a return value of zero.
char(n)
Returns the character associated with the ascii value of n. In
effect, this is the complement of the ascii function above.
left(s,n)
Returns the leftmost n characters of string s. This is more
efficient than a call to substr.
right(s,n)
Returns the rightmost n characters of string s.
ltrim(s, c)
Returns a string with the preceding characters in c removed from the
left of s. For instance, ltrim(" hello", "h ") will return "ello".
If c is not specified, whitespace will be trimmed.
rtrim(s, c)
Returns a string with the preceding characters in c removed from the
right of s. For instance, ltrim(" hello", "ol") will return " he".
If c is not specified, whitespace will be trimmed.
trim(s, c)
Returns a string with the preceding characters in c removed from each
end of s. For instance, trim(" hello", "oh ") will return "ell". If
c is not specified, whitespace will be trimmed. The three trim
functions are considerably more efficient than calls to sub or gsub.
min(x1,x2,...,xn)
Returns the lowest number in the series x1 to xn. A minimum of two
and a maximum of 255 numbers may be passed as arguments to Min.
max(x1,x2,...,xn)
Returns the highest number in the series x1 to xn. A minimum of two
and a maximum of 255 numbers may be passed as arguments to Max.
time(year,mon,day,hour,sec) time()
returns a number representing the date & time in seconds since the
Epoch, 00:00:00GMT 1 Jan 1970. The arguments allow specification of
a date/time, while no arguments will return the current time.
systime()
returns a number representing the current date & time in seconds
since the Epoch, 00:00:00 GMT 1 Jan 1970. This function was included
to increase compatibility with Gawk.
strftime(format, n)
returns a string containing the time indicated by n formatted
according to format. See strftime(3) for more details on format
specification. This function was included to increase compatibility
with Gawk.
gmtime(n) gmtime()
returns a string containing Greenwich Mean Time, in the form:-
Fri Jan 8 01:23:56 1999
n is a number specifying seconds since 1 Jan 1970, while a call with
no arguments will return a string containing the current time.
localtime(n) localtime()
returns a string containing the date & time adjusted for the local
timezone, including daylight savings. Output format & arguments are
the same as gmtime.
mktime(str)
The same as mktime() introduced in Gawk 3.1.0. See Gawk's manpage
for a detailed description of what this function does.
and(y,x)
Returns the output of 'y & x'.
or(y,x)
Returns the output of 'y | x'.
xor(y,x)
Returns the output of 'y ^ x'.
compl(y)
Returns the output of '~y'.
lshift(y,x)
Returns the output of 'y << x'.
rshift(y,x)
Returns the output of 'y >> x'.
argcount()
When called from within a function, returns the number of arguments
that were passed to that function.
argval(n[, arg, arg...])
When called from within a function, returns the value of variable n
in the argument list. The optional arg parameters are index elements
used if variable n is an array. You may not specify values for n
that are larger than argcount().
getawkvar(name[, arg, arg...])
Returns the value of global variable "name". The optional arg
parameters work in the same as for argval. The variable specified by
name must actually exist.
gensub(r,s,f[,v])
Implementation of Gawk's gensub function. It should perform exactly
the same as it does in Gawk. See Gawk's documentation for details on
how to use gensub.
The SORTTYPE variable controls if and how arrays are sorted when
accessed using 'for (i in j)'. The value of this variable is a
bitmask, which may be set to a combination of the following values:-
0 No Sorting
1 Alphabetical Sorting
2 Numeric Sorting
4 Reverse Order
A value for SORTTYPE of 5, therefore, indicates that the array is to be
sorted Alphabetically, in Reverse order.
Awka also supports the FIELDWIDTHS variable, which works exactly as it
does in Gawk.
If the FIELDWIDTHS variable is set to a space separated list of
positive numbers, each field is expected to have fixed width, and awka
will split up the record using the widths specified in FIELDWIDTHS.
The value of FS is ignored. Assigning a value to FS overrides the use
of FIELDWIDTHS, and restores the default behaviour.
Awka also introduces the SAVEWIDTHS variable. This applies when
FIELDWIDTHS is in use, and $0 is being rebuilt following a change to a
$1..$n field variable.
If the SAVEWIDTHS variable is set to a space separated list of positive
numbers, each output field will be given a fixed width to match these
numbers. $n values shorter than their specified width will be padded
with spaces; if they are longer than their specified width they will be
truncated. Additional values to those specified in SAVEWIDTHS will be
separated using OFS.
Awka 0.7.5 supports the inet/coprocessing features introduced in Gawk
3.1.0. See the documentation accompanying the Gawk source, or visit
http://home.vr-web.de/Juergen.Kahrs/gawk/gawkinet.html for details on
how these work.
EXAMPLES
The command-line arguments above provide a range of ways in which awka
may be used, from output of C code to stdout, through to an automatic
translation compile and execution of the AWK program.
(a) Producing C code:-
1. awka -f myprog.awk >myprog.c
2. awka -c main_one -f myprog.awk -f other.awk >myprog.c
(b) Producing C code and an executable:-
awka -X -f myprog.awk -f other.awk
(c) Producing the C and Executable, run the executable:-
awka -x -f myprog.awk -f other.awk -- input.txt
Afterwards, you could run the executable directly, as in:-
awka.out input.txt
Running the same program using an interpreter such as mawk would be
done as follows:-
mawk -f myprog.awk -f other.awk input.txt
The following will run the program, passing it -v on the command-line
without it being interpreted as an 'option':-
awka.out -We -v input.txt, OR
awka -x -f myprog.awk -- -We -v input.txt
(d) Producing and running the executable, ensuring it
and the C program file are automatically removed:-
awka -x -t -f myprog.awk -f other.awk -- input.txt
(e) A simplistic example of how awka might be used in a Makefile:-
myprog: myprog.o
gcc myprog.o -lawka -lm -o myprog
myprog.o: myprog.c
myprog.c: myprog.awk
awka -f myprog.awk >myprog.c
LINKING AWKA-GENERATED CODE
The C programs produced by awka call many functions in libawka.a. This
library needs to be linked with your program for a workable executable
to be produced.
Note that when using the -x and -X arguments this is automatically
taken care of for you, so linking is only an issue when you use Awka to
produce C code, which you then compile yourself. Many people many only
wish to use Awka in this way, and never use awka-generated code as part
of larger applications. If this is you, you needn't worry too much
about this section.
As well as linking to libawka.a, your program will also need to be
linked to your system's math library, typically libm.a or libm.so.
Typical compiler commands to link an awka executable might be as
follows:-
gcc myprog.c -L/usr/local/lib -I/usr/local/include -lawka -lm -o
myprog
OR
awka -c my_main -f myprog.awk >myprog.c
gcc -c myprog.c -I/usr/local/include -o myprog.o
gcc -c other.c -o other.o
gcc myprog.o other.o -L/usr/local/lib -lawka -lm -o myapp
If you are not sure of how your compiler works you should consult the
manpage for the compiler. In release 0.7.5 Awka introduced
Gawk-3.1.0's inet and coprocess features. On some platforms this may
require you to link to the socket and nsl libraries (-lsocket -lnsl).
To check this, look at config.h after running the configure script.
The #define awka_SOCKET_LIBS indicate what, if any, extra libraries are
required on your system.
USING awka -c
The -c option, as described previously, replaces the main() function
with a function name of your choosing. You may then link this code to
other C or C++ code, and thus add AWK functionality to a larger
application.
The command line "awka -c matrix 'BEGIN { print "what is the matrix?"
}'" will produce in its output the function "int matrix(int argc, char
*argv[])". Obviously, this replaces the main() function, and the argc
and argv variables are used the same way - they handle what awka thinks
are command-line arguments. Hence argv is an array of pointers to char
*'s, and argc is the number of elements in this array. argv[0], from
the command-line, holds the name of the running program. You can
populate as many argv[] elements as you like to pass as input to your
AWK program. Just remember this array is managed by your calling
function, not by awka.
That's just about it. You should be able to call your awka function
(eg matrix()) as many times as you like. It will grab a little bit of
memory for itself, but you should see no growing memory use with each
call, as I've taken quite some time to eliminate any potential memory
leaks from awka code.
Oh, one more thing, exit and abort statements in your AWK program code
will still exit your program altogether, so be careful of where & how
you use them.
GOING FURTHER
Awka also allows you to create your own C functions and have them
accessible in your AWK programs as if they were built-in to the AWK
language. See the awka-elm and awka-elmref manpages for details on how
this is done.
FILES
libawka.a, libawka.so, awka, libawka.h, libdfa.a, dfa.h
SEE ALSO
awk(1), mawk(1), gawk(1), awka-elm(5) awka-elmref(5), cc(1), gcc(1)
Aho, Kernighan and Weinberger, The AWK Programming Language, Addison-
Wesley Publishing, 1988, (the AWK book), defines the language, opening
with a tutorial and advancing to many interesting programs that delve
into issues of software design and analysis relevant to programming in
any language.
The GAWK Manual, The Free Software Foundation, 1991, is a tutorial and
language reference that does not attempt the depth of the AWK book and
assumes the reader may be a novice programmer. The section on AWK
arrays is excellent. It also discusses Posix requirements for AWK.
Like you, I should probably buy & read these books some day.
MISSING FEATURES
awka does not implement gawk's internal variable IGNORECASE. Gawk's
/dev/pid functions are also absent.
Nextfile and next may not be used within functions. This will never be
supported, unlike the previous features, which may be added to awka
over time. Well, so I thought. As of release 0.7.3 you _can_ use
these from within functions.
AUTHOR
Andrew Sumner (andrewsumner@yahoo.com)
The awka homepage is at http://awka.sourceforge.net. The latest
version of awka, along with development 'snapshot' releases, are
available from this page. All major releases will be announced in
comp.lang.awk. If you would like to be notified of new releases,
please send me an email to that effect. Make sure you preface any
email messages with the word "awka" in the title so I know its not
spam.
Version 0.7.x Aug 8 2000 AWKA(1)