Grep and remove lines with a blank field value

Question

I was wondering if there's any command to look for blank field values of a text file and remove the entire line.

Example

 Hello:Its Me
 Hello:How are you
 Hello:
 Hello:Bye

And expected output

 Hello:Its Me
 Hello:How are you
 Hello:Bye

Answer 1

Very standard case, the simplest solution with awk would be

awk -F: '$2 != ""' file

and with grep:

grep :. file 

Answer 2

If you mean to skip Hello: lines you can use something like:

awk -F: '{if($2 != "") print }' input_file 

Answer 3

At least with GNU awk, and I think with any version of awk, the default action when something evaluates to true is to print. So, if you set the field delimiter to :, to print lines that have a second field, all you need is:

$ awk -F: '$2' file
Hello:Its Me
Hello:How are you
Hello:Bye

However, this will also print cases where the second field is whitespace (a space, or a tab etc), but will not print the line if second field is one or multiple 0s, because awk evaluates this as false.

Answer 4

Sometimes it is easier to define the remove conditions (grep -v). Example remove when last field is empty:

grep -v ':$' file