Extract Lines when Column K is empty with AWK/Perl
You need to specifically set the field separator to a TAB character:
> cat qq.in foo 78 xxx bar yyy qux 99 zzz xuq xyz> cat qq.in | awk 'BEGIN {FS="\t"} $2=="" {print}' bar yyy xuq xyzThe default behaviour for awk is to treat an FS of SPACE (the default) as a special case. From the man page:
In the special case that
FSis a single space, fields are separated by runs of spaces and/or tabs and/or newlines. (my italics)
perl -F/\t/ -lane 'print unless $F[1] eq q//' myfile.txtCommand Switches
-Ftells Perl what delimiter to autosplit on (tabs in this case)-aenables autosplit mode, splitting each line on the specified delimiter to populate an array@F-lautomatically appends a newline"\n"at the end of each printed line-nprocesses the file line-by-line-etreats the first quoted argument as code and not a filename