The if command

Assume you have the following file:

50
30
80
70
20
90 

Now, let's filter the values:

$ awk '{if ($1 > 50) print $1}' myfile  

The if statement checks every value and, if it's greater than 50, it will print it.

You can use else clauses like this:

$ awk '{
if ($1 > 50)
{
x = $1 * 2
print x
} else
{
x = $1 * 3
print x
}}' myfile

If you don't use brackets {} to enclose your statements, you can type them on the same line with a semicolon:

$ awk '{if ($1 > 50) print $1 * 2;  else print $1 * 3}' myfile  

Note that you can save this code into a file and assign it to the awk command using the -f option, as we will see later on this chapter.