Today I Learned - Munging Epochs using awk

So today I had a requirement to convert some Epoch-formatted dates, located in a CSV file, into human-readable dates...

So today I learned about awk vs. gawk, and the strftime() function ...

I also learned that awk on macOS isn't the same as "real" Gnu awk ( aka gawk ), hence the need for gawk ...

I started by installing gawk: -

brew install gawk

and then updated my PATH to reflect it: -

PATH="/opt/homebrew/opt/gawk/libexec/gnubin:$PATH"

Using an example of my data: -

cat file.txt

1681486514
1681990787
1681992853
1681712949

which is WAY simpler than my real data, I was then able to munge it using awk ( or, really, gawk ) : -

awk 'BEGIN { FS = ","} ; {$1 = strftime("%c", $1)} 1' file.txt

which returns: -

Fri 14 Apr 16:35:14 2023
Thu 20 Apr 12:39:47 2023
Thu 20 Apr 13:14:13 2023
Mon 17 Apr 07:29:09 2023

I'd previously done much the same using Excel, via a formula: -

=F17/86400+DATE(1970,1,1)

where cell F17 contained the Epoch-formatted date

But scripts are so much more fun ...