$ awk 'BEGIN {
  PI = 3.14159265
  x = -10
  y = 10
  result = atan2 (y,x) * 180 / PI;

  printf "The arc tangent for (x=%f, y=%f) is %f degrees\n", x, y, result
}'

The output result is:

The arc tangent for (x=-10.000000, y=10.000000) is 135.000000 degrees

$ awk 'BEGIN {
  PI = 3.14159265
  param = 60
  result = cos(param * PI / 180.0);

  printf "The cosine of %f degrees is %f.\n", param, result
}'

The output result is:

The cosine of 60.000000 degrees is 0.500000.

$ awk 'BEGIN {
  PI = 3.14159265
  param = 30.0
  result = sin(param * PI /180)

  printf "The sine of %f degrees is %f.\n", param, result
}'

The output result is:

The sine of 30.000000 degrees is 0.500000.

$ awk 'BEGIN {
  param = 5
  result = exp(param);

  printf "The exponential value of %f is %f.\n", param, result
}'

The output result is:

The exponential value of 5.000000 is 148.413159.

$ awk 'BEGIN {
  param = 5.5
  result = log (param)

  printf "log(%f) = %f\n", param, result
}'

The output result is:

log(5.500000) = 1.704748

$ awk 'BEGIN {
  param = 1024.0
  result = sqrt(param)

  printf "sqrt(%f) = %f\n", param, result
}'

The output result is:

sqrt(1024.000000) = 32.000000

$ awk 'BEGIN {
  param = 5.12345
  result = int(param)

  print "Truncated value =", result
}'

The output result is:

Truncated value = 5

$ awk 'BEGIN {
  print "Random num1 =" , rand()
  print "Random num2 =" , rand()
  print "Random num3 =" , rand()
}'

The output result is:

Random num1 = 0.237788
Random num2 = 0.291066
Random num3 = 0.845814

$ awk 'BEGIN {
  param = 10

  printf "srand() = %d\n", srand()
  printf "srand(%d) = %d\n", param, srand(param)
}'

The output result is:

srand() = 1
srand(10) = 1417959587

$ awk 'BEGIN {
    str = "Hello, World"

    print "String before replacement = " str

    gsub("World", "Jerry", str)

    print "String after replacement = " str
}'

The output result is:

String before replacement = Hello, World
String after replacement = Hello, Jerry

$ awk 'BEGIN {
    str = "Hello, World"

    print "String before replacement = " str

    sub("World", "Jerry", str)

    print "String after replacement = " str
}'

The output result is:

String before replacement = Hello, World
String after replacement = Hello, Jerry

$ awk 'BEGIN {
    str = "Hello, World !!!"
    subs = substr(str, 1, 5)

    print "Substring = " subs
}'

The output result is:

Substring = Hello

$ awk 'BEGIN {
    str = "One Two Three"
    subs = "Two"

    ret = index(str, subs)

    printf "Substring \"%s\" found at %d location.\n", subs, ret
}'

The output result is:

Substring "Two" found at 5 location.

$ awk 'BEGIN {
    str = "Hello, World !!!"

    print "Length = ", length(str)
}'

The output result is:

Substring "Two" found at 5 location.

$ awk 'BEGIN {
    str = "Hello, World !!!"
    subs = substr(str, 1, 5)

    print "Substring = " subs
}'

The output result is:

Substring = Hello

$ awk 'BEGIN {
    str = "One Two Three"
    subs = "Two"

    ret = match(str, subs)

    printf "Substring \"%s\" found at %d location.\n", subs, ret
}'

The output result is:

Substring "Two" found at 5 location.

$ awk 'BEGIN {
    str = "One,Two,Three,Four"

    split(str, arr, ",")

    print "Array contains following values"

    for (i in arr) {
        print arr[i]
    }
}'

The output result is:

Array contains following values
One
Two
Three
Four

$ awk 'BEGIN {
    str = "HELLO, WORLD !!!"

    print "Lowercase string = " tolower(str)
}'

The output result is:

Lowercase string = hello, world !!!

$ awk 'BEGIN {
    str = "hello, world !!!"

    print "Uppercase string = " toupper(str)
}'

The output result is:

Uppercase string = HELLO, WORLD !!!

$ awk 'BEGIN {
    str = sprintf("%s", "Hello, World !!!")

    print str
}'

The output result is:

Hello, World !!!

$ awk 'BEGIN {
    print "十进制数 = " strtonum("123")
    print "八进制数 = " strtonum("0123")
    print "十六进制数 = " strtonum("0x123")
}'

The output result is:

十进制数 = 123
八进制数 = 83
十六进制数 = 291

$ awk 'BEGIN {
    print "Number of seconds since the Epoch = " mktime("2014 12 14 30 20 10")
}'

The output result is:

Number of seconds since the Epoch = 1418604610

$ awk 'BEGIN {
    print strftime("Time = %m/%d/%Y %H:%M:%S", systime())
}'

The output result is:

Time = 12/14/2014 22:08:42

awk 'BEGIN{now=systime();print now}'

The output result is:

1343210982

$ awk 'BEGIN {
    num1 = 10
    num2 = 6

    printf "(%d AND %d) = %d\n", num1, num2, and(num1, num2)
}'

The output is:

(10 AND 6) = 2

$ awk 'BEGIN {
    num1 = 10

    printf "compl(%d) = %d\n", num1, compl(num1)
}'

The output is:

compl(10) = 9007199254740981

$ awk 'BEGIN {
    num1 = 10

    printf "lshift(%d) by 1 = %d\n", num1, lshift(num1, 1)
}'

The output is:

lshift(10) by 1 = 20

$ awk 'BEGIN {
    num1 = 10

    printf "rshift(%d) by 1 = %d\n", num1, rshift(num1, 1)
}'

The output is:

rshift(10) by 1 = 5

$ awk 'BEGIN {
    num1 = 10
    num2 = 6

    printf "(%d OR %d) = %d\n", num1, num2, or(num1, num2)
}'

The output is:

(10 OR 6) = 14

$ awk 'BEGIN {
    num1 = 10
    num2 = 6

    printf "(%d XOR %d) = %d\n", num1, num2, xor(num1, num2)
}'

The output is:

(10 bitwise xor 6) = 12

$ awk 'BEGIN {
    cmd = "tr [a-z] [A-Z]"
    print "hello, world !!!" |& cmd
    close(cmd, "to")
    cmd |& getline out
    print out;
    close(cmd);
}'

The output is:

HELLO, WORLD !!!

• The first statement cmd = "tr [a-z] [A-Z]" establishes a two-way communication channel in AWK.
• The second statement print provides input to the tr command. &| indicates two-way communication.
• The third statement close(cmd, "to") closes the to process after execution is completed.
• The fourth statement cmd |& getline out uses the getline function to store the output in the out variable.
• The subsequent output statement prints the content of the output, and finally the close function closes cmd.

$ awk 'BEGIN {
    arr[0] = "One"
    arr[1] = "Two"
    arr[2] = "Three"
    arr[3] = "Four"

    print "Array elements before delete operation:"
    for (i in arr) {
        print arr[i]
    }

    delete arr[0]
    delete arr[1]

    print "Array elements after delete operation:"
    for (i in arr) {
        print arr[i]
    }
}'

The output is:

Array elements before delete operation:
One
Two
Three
Four

Array elements after delete operation:
Three
Four

$ awk 'BEGIN {
    print "Hello, World !!!"

    exit 10

    print "AWK never executes this statement."
}'

The output is:

Hello, World !!!

Use getline to read a line from the file marks.txt and output it:

$ awk '{getline; print $0}' marks.txt 

AWK reads a line from the file marks.txt and stores it in variable 0. In the next statement, we use getline to read the next line. Therefore AWK reads the second line and stores it in variable 0. Finally, AWK uses print to output the content of the second line. This process continues until the end of the file.

When the pattern matches successfully, the program does not perform any operation:

$ awk '{if ($0 ~/Shyam/) next; print $0}' marks.txt

First create two files. The contents of file1.txt are as follows:

file1:str1
file1:str2
file1:str3
file1:str4

The contents of file2.txt are as follows:

file2:str1
file2:str2
file2:str3
file2:str4

Now let's test the nextfile function.

$ awk '{ if ($0 ~ /file1:str2/) nextfile; print $0 }' file1.txt file2.txt

The output is:

file1:str1
file2:str1
file2:str2
file2:str3
file2:str4

Create a file functions.awk with the following content:

function addition(num1, num2)
{
    result = num1 + num2

    return result
}

BEGIN {
    res = addition(10, 20)
    print "10 + 20 = " res
}

Execute the file:

$ awk -f functions.awk 
10 + 20 = 30

$ awk 'BEGIN { ret = system("date"); print "Return value = " ret }'

The output is:

Sun Dec 21 23:16:07 IST 2014
Return value = 0