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How to filter empty line with a 'cut' command?

I have a tab delimited file with a few fields:

f1    f2   f3 
a     b    c
a     c     
d     e    
f     g    a

I want to extract the 3rd column with a 'cut'command:

cut -f3 t

This works. However, how can I filter the empty line in the output? As it can be seen, the 2nd and 3rd lines are empty after they are extracted.

Solution

  • To remove empty output:

    $ cut -f3 file | grep .
f3
c
a

    Or:

    $ awk -F'\t' '$3 {print $3}' file
f3
c
a

    To replace the missing output with a filler:

    $ awk -F'\t' '{if ($3) print $3; else print "FILL"}' file
f3
c
FILL
FILL
a

    Or, for people who like the more compact ternary statement:

    $ awk -F'\t' '{print ($3?$3:"FILL")}' file
f3
c
FILL
FILL
a

    Example with multiple words in field 3

    $ cat file2
f1      f2      f3
f       g       a b c d
$ cut -f3 file2 | grep .
f3
a b c d
$ awk -F'\t' '$3 {print $3}' file2
f3
a b c d