Print min and max with awk

Why wont this awk script work, where I want to print the min and max of an input by just reading the data once. I would also like to initialize the min and max variable with the first value of the data.

Say I have a file

JavaScript
​x
 
a 14a 34a 234a 2345a 1a 24​

I am using awk to print the min and max with:

cat test.txt | awk 'BEGIN {min=$2; max=$2} {if ($2 < min) {min=$2}; if ($2 > max) {max=$2} } END {print "min: " min "max: " max}'

JavaScript
 
cat test.txt | awk 'BEGIN {min=$2; max=$2} {if ($2 < min) {min=$2}; if ($2 > max) {max=$2} } END {print "min: " min "max: " max}'​

But I am getting a result of:

min: max: 2345

JavaScript
 
min: max: 2345​

I dont understand why min is set to blank?

Answer

The BEGIN {} block is processed before the first line so $2 is undefined.

$ cat file
a 14
a 34
a 234
a 2345
a 1
a 24
$ awk 'NR == 1  { min = max = $2; next }
       $2 > max { max = $2 }
       $2 < min { min = $2 }
       END      { print "min: " min ", max: " max }' file
min: 1, max: 2345

JavaScript
 
$ cat filea 14a 34a 234a 2345a 1a 24$ awk 'NR == 1  { min = max = $2; next }       $2 > max { max = $2 }       $2 < min { min = $2 }       END      { print "min: " min ", max: " max }' filemin: 1, max: 2345​

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Answer