bash - Unique entry set in the first column of all csv files under directory -

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i have list of comma separated files under directory. there no headers, , unfortunately not same length each row.

i want find unique entry in first column across files.

what's quickest way of doing in shell programming?

awk -f "," '{print $1}' *.txt | uniq

seems uniq entries of each files. want files.

shortest still using awk (this print row)

awk -f, '!a[$1]++' *.txt

to first field

awk -f, '!a[$1]++ {print $1}' *.txt

Th