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LINUX AWK Tutorial Series | Chapter 11

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LINUX AWK Tutorial Series | Chapter 11

In this post, I am going to share the functions in AWK.

Functions in AWK can be built-in functions and user-defined functions

Built-In Functions: These are pre-defined functions that are already available. We can directly call and use them.

Let's see some of them

sqrt(x): positive square root of a number x
init(x): Truncate x to an integer value for any positive and negative number.
exp(x): Gives exponential of x
rand(): it returns any random value between 0 and 1. But will not return 0 or 1. It will random in one awk execution.
srand(x): Provide seed value of x random function. if x is not present date and time is used as an seed value.
length(x) : Length of particular string
index(s1,s2): Position of a string s2 in larger string s1.
substr(s,a,b): Extract a substring from larger string s. a is the index position to start reading and b is the total characters to be read starting from position a.
system(): Run unix command within AWK



We can see many arithmetic functions, I will not mention all but a few more which you can look out for is log(x), sin(x), cos(X)

Example 1:

Let's perform the basic operations


It's very easy. Try more at Home

Example 2:

Random number generation. If you observe I have used the rand() and srand() function to generate random numbers.

[himanshu@oel7 AWK]$ cat random_funtion
BEGIN{
srand()
print rand()
}
[himanshu@oel7 AWK]$ awk -f random_funtion
0.0376296

Try at Home: If you remove srand from the above script file what will happen.


Example 3:


Using a string function.

[himanshu@oel7 AWK]$ cat string_function
BEGIN{
print length("Himanshu");
print index("Himanshu","man")
}
[himanshu@oel7 AWK]$ awk -f string_function
8
3
Example 4:

Display date using AWK.

[himanshu@oel7 AWK]$ awk 'BEGIN{system("date")}'
Thr Nov 5 07:28:49 IST 2020

Next chapter I will tell how to create user-defined function in AWK.

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