How can I replace rows containing ONLY number ' 0' with blank rows using AWK?

Question

I am looking for a command that would replace the rows containing ONLY number 0 in their columns, with 'blank' lines.

e.g. I have below input:

Taj_Mahal                                             Agra                       
                                                        0                             
                                                        0               
Chichen_Itza                                          Yucatán              
                                                        0                             
                                                        0               
Christ_the_Redeemer                                   Rio_de_Janeiro              
                                                        0                             
                                                        0               
Colosseum                                             Rome                 
                                                        0                             
                                                        0               
Great_Wall_of_China                                   China                      
                                                        0                             
                                                        0               
Machu_Picchu                                          Cuzco_Region                     
                                                        0                             
                                                        0               
Petra                                                 Ma'an_Governorate                   
                                                        0                             
                                                        0               
Great_Pyramid_of_Giza                                 Egypt                   
                                                        0                             
                                                        0               

Below should be the output:

Taj_Mahal                                             Agra                       


Chichen_Itza                                          Yucatán              


Christ_the_Redeemer                                   Rio_de_Janeiro              


Colosseum                                             Rome                 


Great_Wall_of_China                                   China                      


Machu_Picchu                                          Cuzco_Region                     


Petra                                                 Ma'an_Governorate                   


Great_Pyramid_of_Giza                                 Egypt                   

Answer 1

After editing your post, it appears that the lines in your sample input do not contain "ONLY" the zero. They contain many spaces and a zero. If this is the case, with awk:

awk 'NF==1 && $1=="0" { $0="" } { print }'

$0 refers to the entire line. NF refers to the number of fields. $1 refers to the first field. By default, awk strips leading/trailing blanks.

Alternatively, using regular expression matching:

 awk '/^ *0 *$/ { $0="" } { print }'

The solution could be made more succinct (and cryptic) by replacing { print } with 1, but, even so, sed would still be more concise:

sed 's/^ *0 *$//'

Note that the first awk suggestion ignores leading and trailing blanks (which may include tabs and other locale-dependent characters). The second awk and the sed approaches only ignore leading/trailing spaces.