I've run into some problems with editing a text file I've received due to some missing values in a specific column for some rows. For example, here is what the file looks like (mostly):ID10    dad    prbM    ATGDID11    mom    prbF    CDSFID12    mom        CGDSID13    dad    prbF    FSDDID14    mom        FDSFAs you can see, sometimes the prb is not provided for every entry. I've found that when an entry is not present, there are two tab separations. Is there a way to insert a string between the tabs? For example, something like this:ID10    dad    prbM    ATGDID11    mom    prbF    CDSFID12    mom    none    CGDSID13    dad    prbF    FSDDID14    mom    none    FDSF
insert string for missing value
sed;awk
With awk, assuming your fields are actually separated by tabs:awk -F '\t' -v OFS='\t' '$3 == {$3 = none};1' input.txtThis:Sets the input field separator to a single tab (-F '\t')Sets the output field separator to a tab (-v OFS='\t')Checks if the third field is empty ($3 == ), and if so, sets it to the string noneAnd always prints the line (1).