awk: Statements(3)

1. Comprehensive Iterative Example:
./script_1:

 #! /bin/bash  
   
 awk -v num=$1 'BEGIN {  
   n=num;  
   m=n=(num>=2)? n:2;  
   factors = "";  
   for(k=2; (m>1) && (k^2 <= n);)  
   {  
     if(int(m % k) != 0)  
     {   
       k++;  
       continue;  
     }  
   
     m/=k;  
     factors = (factors == "")? ("" k) : (factors "*" k);  
   }  
   
   if( (m > 1) && ( m < n) )  
     factors = factors "*" m;  
   print n, (factors=="")? "is a prime number":("=" factors)  
 }'  

terminal:

 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ ./script_1 2  
 2 is a prime number  
 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ ./script_1 3  
 3 is a prime number  
 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ ./script_1 4  
 4 =2*2  
 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ ./script_1 5  
 5 is a prime number  
 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ ./script_1 6  
 6 =2*3  

2. Array Member Testing
awk needs contant time to do array member testing.
text2:

 1 Chicago  
 4 Boston  
 3 Atlantic  

./script_1:

 #! /bin/bash  
   
 awk '{  
   cities[$1]=$2;  
 }  
 END {  
   for(i=1; i<=4; i++)  
   {  
     if (i in cities)  
       print i ":" cities[i];  
   }  
 }' text2  

terminal:

 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ ./script_1  
 1:Chicago  
 3:Atlantic  
 4:Boston  

3. awk Flow Control
Skip further patterns for this record:
text 2:

 start Chicago  
 skip Boston  
 end Atlantic  

script_1:
After executing next, awk will ignore all remaining statements, including the "print $0"

 #! /bin/bash  
   
 awk '/skip/ { next; print $0;}  
 { print $0; } ' text2  

terminal:

 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ ./script_1  
 start Chicago  
 end Atlantic 

=======================================
Exit from current awk script:
text2:

 start Chicago  
 process Los Angeles  
 exit Boston  
 end Atlantic  

script_1:

 #! /bin/bash  
   
 awk '/exit/ { exit 20; }  
 { print $0; } ' text2  
   

terminal:

 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ ./script_1  
 start Chicago  
 process Los Angeles  
 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ echo $?  
 20