Merging two outputs in shell script

You can use awk:

awk 'FNR==NR{a[$2];print;next} !($2 in a)' file1 file2A BC DE FG HI JK L

shell unix command-line merge

If the order of entries is not important, you can sort on the 2nd column and uniquefy:

sort -u -k2 file1 file2

Both -u and -k are specified in the POSIX standard

This wouldn't work if there are repeated entries in the 2nd column of file1.

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