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awk: print lines only when two lines with $NF == "string" found.

awk: print lines only when two lines with $NF == "string" found.

awk: print lines only when two lines with $NF == "string" found.



print no line if only one or more than two has been found.

$ echo "1 2 3 stringA\n3 4 5 stringA"|awk '$NF == "stringA"'
1 2 3 stringA
3 4 5 stringA

current workaround:
TEST_INPUT="1 2 3 stringA\n3 4 5 stringB"
if [ `echo ${TEST_INPUT}|awk '$NF == "stringA"'|wc -l` -eq 2 ]
echo ${TEST_INPUT}|awk '$NF == "stringA"'

can it be done with the only 'awk' command in:

echo "1 2 3 stringA\n3 4 5 stringB"|awk '$NF == "stringA"'

RE: awk: print lines only when two lines with $NF == "string" found.


This is a typical case for double passing : first just count, when just output :

CODE --> command-line

awk 'FNR==NR{$NF=="stringA"&&c++;next}c==2&&$NF=="stringA"' /input/file /input/file 

In case your input will come from the standard input, will need the shell's process substitution feature :

CODE --> command-line

awk 'FNR==NR{$NF=="stringA"&&c++;next}c==2&&$NF=="stringA"' <( echo "$TEST_INPUT" ) <( echo "$TEST_INPUT" ) 

In case the input is huge, is preferable to use optimized code, even if it is abit longer :

CODE --> command-line

awk 'FNR==NR{$NF=="stringA"&&c++;next}FNR==1&&c!=2{exit}$NF=="stringA"' /input/file /input/file

# or

awk 'FNR==NR{$NF=="stringA"&&c++;next}FNR==1&&c!=2{exit}$NF=="stringA"' <( echo "$TEST_INPUT" ) <( echo "$TEST_INPUT" ) 


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