Unix AWK madness

Ok, not really ‘madness’ but still this issue somewhat made me feel like I’m loosing my mind at some point…

If you are using Unix’s awk on a regular basis, you might encounter a case where you want to filter a file by a column containing numeric values. You can do this by a simple statement if, for example, you want to filter in the first column (the ‘$1’ in the code):

awk '{if($1+0 <= 0.05) print; }'

The line above reads: If the value of the first entry in a row is smaller than 0.05, print the whole line.

NOTE: You could also use exponential representation, e.g. 5e-2, 1e-5, etc.

IMPORTANT: You need to add the ‘+0’ to make awk convert the column values into numeric (‘adding 0’ so we do not change the value). I first did not know about this, which led to a weird behavior of awk (i.e. some values which matched the criteria were not filtered, but only rows with a value below the cutoff were present in the output). Of course, this was entirely me not being knowledgeable enough to use awk properly…

Just wanted to put this information out there, hope this helps someone encountering the same issue in the future!

Until then, farewell!