How can I convert timestamps in a column to a date?

Found something here: Stackoverflow - Convert from unixtime at command line.

Came up with this:

awk -F"," '{OFS=","; $1=strftime("%Y-%m-%d %H:%M:%S", $1); print $0}' file

• -F"," to use a field separator of ,,
• OFS=","; so that the output fields are also separated by a ,,
• $1=strftime("%Y-%m-%d %H:%M:%S", $1); to change the value of the first field $1 into the specified format, and
• print $0; to print the whole line.

Like this perhaps

perl -pe 'use POSIX qw(strftime); s/^(\d+)/strftime "%F %H:%M:%S", localtime($1)/e' 

If you like awk you can use external command date with any date formats

awk -F, -v OFS="," '{("date +%F\ %T -d @"$1)|getline $1}1'