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bash file comparison line by line with selected string

rated 0 times [ 0] [ 0] / answers: 1 / hits: 3503 / 1 Year ago, sun, november 20, 2022, 12:11:12

let us say i have two files a.txt, b.txt

a.txt



87621   3bde   NDF

87621   2dfg   NDF

87621   cdef   NDF

87621   abcd   NDF



b.txt



93291   abcd   NDF

93291   2dfg   NDF

93291   adbf   NDF

93291   gdrg   NDF

My script should create a file , by matching column 2 of both the files
and create a file with matching string in new file c.txt like below

c.txt



2dfg

abcd

I tried several options, but not succeded, can you help !

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lawain

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2 Years ago

answered 1 Year ago darpose · Accepted Answer

comm -12 <(awk '{print $2}' a.txt | sort) <(awk '{print $2}' b.txt | sort) > c.txt

Explanation

<(...) is a process substitution. i.e. the output of the commands within the (...) is substituted and used as the two inputs to comm.

awk '{print $2}' a.txt prints only the second field of each line.

sort sorts the output ready for input into comm.

comm compares two sorted files. The -12 flags suppress the lines that are unique to each file, only printing the common lines (see man comm for more details).