mawk

Implementation of programming language AWK

mawk is AWK interpreter written in C by Mike Brennan. It is considered to be the most efficient implementation of AWK and is system default on Ubuntu/Debian Linux.

mawk implements POSIX 1003.2 standard of the language and has a number of useful extensions.

Links:

Examples:

Hello, World!:

Example for versions Jawk 1.02, gawk 3.1.6, mawk 1.3.3

The printing is done with BEGIN pattern, i.e., before processing the input. 

BEGIN { print "Hello, World!" }

Factorial:

Example for versions Jawk 1.02, gawk 3.1.6, mawk 1.3.3

This example uses iterative factorial definition. Individual statements within code block can be separated with semicolons (;) or new lines. 

BEGIN {
    f = 1
    print "0! = " f
    for (i=1; i<17; i++) {
        f *= i
        print i "! = " f
    }
}

Fibonacci numbers:

Example for versions Jawk 1.02, gawk 3.1.6, mawk 1.3.3

This example uses iterative definition of Fibonacci numbers. fib is an associative array, and pr is a string. 

BEGIN {
    fib[1] = 1
    fib[2] = 1
    for (i=3; i<17; i++)
        fib[i] = fib[i-1]+fib[i-2]
    pr = ""
    for (i=1; i<17; i++)
        pr = pr fib[i] ", "
    print pr "..." 
}

Quadratic equation:

Example for versions Jawk 1.02, gawk 3.1.6, mawk 1.3.3 
{   A = $1
    B = $2
    C = $3
    if (A == 0) 
        print "Not a quadratic equation"
    else
    {   D = B*B-4*A*C
        if (D == 0)
            print "x = " (-B/2/A)
        else if (D > 0)
        {   print "x1 = " ((-B+sqrt(D))/2/A)
            print "x2 = " ((-B-sqrt(D))/2/A)
        }
        else
        {   print "x1 = (" (-B/2/A) "," (sqrt(-D)/2/A) ")"
            print "x2 = (" (-B/2/A) "," (-sqrt(-D)/2/A) ")"
        }
    }
}

CamelCase:

Example for versions Jawk 1.02, gawk 3.1.6, mawk 1.3.3

mawk provides no function length to get the size of the array, neither it can be used in Jawk — an attempt results in “Cannot evaluate an unindexed array.” runtime error.

Instead we can use the fact that function split returns the number of string fragments it extracted from the string. Otherwise this example is identical to this one. 

{   text = $0;
    N = split(text, words, /[^a-zA-Z]+/);
    for (i=1; i<=N; i++) {
        res = res toupper(substr(words[i],1,1)) tolower(substr(words[i],2));
    }
    print res
}