Why does
awk '{print 3 + 3}'
not work, but:
echo 3|awk '{print $1 + 3}'
does?
Couldn't the first statement just output 6? What is the easiest way of printing the result of a calculation?
asked Mar 8, 2016 at 15:31
3 Answers
AWK statements consist of a pattern and an action: quoting the GNU awk manual
a rule is executed when its pattern matches the current input record
In the first case, you are not providing any input record - so you get no action. In this case, you could use the special pattern BEGIN
awk 'BEGIN {print 3 + 3}'
answered Mar 8, 2016 at 15:38
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1You could also just hit "Enter" again after typing in
awk '{print 3 + 3}'.– WildcardMar 9, 2016 at 5:13
Equally well you could do
awk 'END {print 3 + 3}'
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This is not "equally" good as steeldriver's answer. When the only action statements in an
awkscript are associated with theBEGINpseudo-pattern, the script runs immediately, without looking at its input. With your answer,awkreads (and ignores/discards) its input until it reaches EOF, and only then executes the statement. Apr 23, 2016 at 5:54
With bash echo $(( 3 + 3)) or with bc
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so? it doesn't always matter what you specifically ask for. When you are asking a wrong question (such as using the wrong or even sub-optimal tool for a job), a good answer will inform you of that fact. "Q. how do i shoot myself in the foot with a banana?" A. "You don't, you use a gun. Better yet, it's a good idea to avoid shooting yourself in the foot, you should do X instead."....and a lot of wrong questions are the OP metaphorically shooting themselves in the foot.– casMar 8, 2016 at 22:59
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@cas: Unless I am actually trying to learn something about Awk... But, yes, you are right that sometimes it is OK to question the OP's assumptions and intentions. In this case, however, awk is a perfectly capable tool. Mar 9, 2016 at 14:54
awk 'BEGIN{print (2+2)}'<- This?