CODEWITHSUNDEEP
bashshellawk
user1179317
user1179317

Reputation: 2923

Negate condition with awk

I cant seem to figure out how to negate my condition with awk.

For example, lets say I have

g ha
a bb
g hc
f cd
t de
g pf

I can print just the ones with g and starts with h for the first and second column with:

cat test.txt | awk '$1 ~ /g/ && $2 ~ /^h/'

but how do I do the opposite, where I just want to print the ones that are not g and start with h. Basically to have the output:

a bb
f cd
t de
g pf

Upvotes: 0

Views: 207

Answers (3)

Ed Morton
Ed Morton

Reputation: 203995

The negation (opposite) of $1 ~ /g/ && $2 ~ /^h/ or any other condition is simply sticking ! at the front of it:

$ awk '!($1 ~ /g/ && $2 ~ /^h/)' file
a bb
f cd
t de
g pf

but you can also apply boolean algebra to that (!(a && b) = !a || !b) to get:

$ awk '$1 !~ /g/ || $2 !~ /^h/' file
a bb
f cd
t de
g pf

Upvotes: 0

The fourth bird
The fourth bird

Reputation: 163457

You could also negate the whole match using !

As the first field is always a single character you can check if it is g without using a regex notation because $1 ~ /g/ will still match if there is a g somewhere in the string.

awk '!($1 == "g" && $2 ~ /^h/)' test.txt

Output

a bb
f cd
t de
g pf

Upvotes: 0

Cyrus
Cyrus

Reputation: 88766

If $1 ~ /g/ && $2 ~ /h/ is true then continue with the next line otherwise output the current line.

awk '$1 ~ /g/ && $2 ~ /h/{next} {print}' test.txt

Output:

a b
f c
t d
g p

Upvotes: 2

Related Questions