# generate the 2 basic files
cat /dev/urandom | tr -dc 'a-f0-9' | fold -w 32 | head -n 30 > random1.csv
cat /dev/urandom | tr -dc 'a-f0-9' | fold -w 32 | head -n 30 > random2.csv
    # generate common lines
cat /dev/urandom | tr -dc 'a-f0-9' | fold -w 32 | head -n 3 > common.csv
    # mix the common lines into the 2 files
cat random1.csv common.csv | shuf > random11.csv
cat random2.csv common.csv | shuf > random22.csv

$ cat common.csv
8b1df61042e621bb3cd3ba43942b5ada
71b2368e90c6eb038e84ef29446c0dec
56697847ec43cc181a556625ec880d85
    # select one common line and look for it in the 2 files
$ grep -n 8b1df61042e621bb3cd3ba43942b5ada random11.csv
14:8b1df61042e621bb3cd3ba43942b5ada
$ grep -n 8b1df61042e621bb3cd3ba43942b5ada random22.csv
33:8b1df61042e621bb3cd3ba43942b5ada