Formatting date strings in a file with linux bash shell

Question

When I cat the file an example of the output format is:

ok: servername Mon May 23 00:00:00 EDT 2018
ok: servername Thu Jul 16 00:00:00 EDT 2019

Answer 1

With GNU date, you can specify an input file containing all your date strings; combined with cut and paste:

paste -d ' ' \
    <(cut -d ' ' -f-2 infile) \
    <(date -f <(cut -d ' ' -f3- infile) '+%m/%d/%Y')

Output:

ok: servername 05/23/2018
ok: servername 07/16/2019

This uses process substitution to build a temporary input file for date -f, and for paste to build a new output file.