awk: one-line examples(1)

1. wc command simulation:
text:

 Hello Chicago!  
 Hello New York!  
 Hello Los Angeles!  

script_1:

 #! /bin/bash  
   
 awk '{ C+= length($0) + 1; W+=NF;} END { print NR,W,C;}' text  
 #output:  
 #3 8 50  
 #For each record, it will execute the given action, which   
 #track the number of character: "C", number of words(fields): "W"  
 #In the end, we output the record number which is also the number  
 #of lines. We also output W and C, which is number of words and  
 #characters.  
   

2. Sink the data
text is same as above

script_1:

 #! /bin/bash  
   
 cat text >/dev/null  
 #We use cat to "sink" the data.  
   
 awk '' text  
 #same effect with awk, since for each record, we let  
 #awk do nothing  
   

3. Output the content of given file
text is same as above

terminal:

 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ awk '1' text  
 Hello Chicago!  
 Hello New York!  
 Hello Los Angeles!  

4. Output Calculation result of specific column
text2:

 Hello 5  
 world 8  
 Hello 12  
 Chicago 15  

terminal:

 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ awk '{ print $2, log($2); }' text2  
 5 1.60944  
 8 2.07944  
 12 2.48491  
 15 2.70805  

5. output some percentage of lines of records
text2:

 1 Hello  
 2 World  
 3 Hello  
 4 Chicago!  
 5 Hello  
 6 New York!  
 7 Hello  
 8 World  
 9 Hello  
 10 Chicago!  
 11 Hello  
 12 New York!  
 13 Hello  
 14 World  
 15 Hello  
 16 Chicago!  
 17 Hello  
 18 New York!  

terminal:

 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ awk 'rand()<0.3' text2  
 9 Hello  
 12 New York!  
 15 Hello  

We are outputting about 30% of lines of records from text2

6. Output sum of specified column records
text2:

 1 Hello  
 2 World  
 3 Hello  
 4 Chicago!  
 5 Hello  

terminal:

 aubinxia@aubinxia-fastdev:~/Desktop/xxdev$ awk -v col=1 '{ sum+=$col;} END { print sum;}' text2  
 15