Explain awk command

Question

Today I was searching for a command online to print next two lines after a pattern and I came across an awk command which I\'m unable to understand.

$ /usr/x         


        

Answer 1

Wonderfully obscure. Will update when time allows.

_ is being used as a variable name. The && is a logical operator that has 2 true actions run together. Once the value of _ is reduced to zero, the 2nd half of the && is false and no output is generated.

print -- "
xxxxx
yyyy
PATTERN
zzz
aa
bbb
ccc
ffffd" | awk '_&&_--;/PATTERN/{_=2}'

output

zzz
aa

debug version

print -- "
xxxxx
yyyy
PATTERN
zzz
aa
bbb
ccc
ffffd" | awk '_&&_--;{print "_="_;print _&&_};/PATTERN/{_=2;print "_="_ }'

output

_=
0
_=
0
_=
0
_=
0
_=2
zzz
_=1
1
aa
_=0
0
_=0
0
_=0
0
_=0
0