Customized date and time display A simple reworking of the Bash date command to my own personal liking. Possibly a rather trivial task; I just wanted the date and time to be in the form of:




Fri Sep 2 2016
11:37 P.M.



I think this accomplishes that:



#!/bin/bash

today() {
    now="$(date | awk '{ OFS=" "; print $1,$2,$3,$6 }')"
    h="$(date "+%H")"
    m="$(date "+%M")"
    if [ $h -gt 12 ]; then 
        echo -e "$now\n$(( $h - 12 )):$m P.M."
    elif [ $h = 12 ]; then
        echo -e "$now\n$h:$m P.M."
    elif [ $h = 00 ]; then
        h=12; echo -e "$now\n$h:$m A.M."
    elif [ $h -le 11 ]; then
        if [ $h -lt 10 ]; then
            h="$(echo $h | cut -c2)"
        fi
        echo -e "$now\n$h:$m A.M."
    fi
}

today


Is there anything I could do to improve this?
Parsing formatted output — as you have done with $(date | awk '{ OFS=" "; print $1,$2,$3,$6 }') — is a dangerous game: it's hard to say exactly what awk should expect as input.  For example, on GNU/Linux, I get:

$ LC_TIME=en_CA.UTF-8 date
Fri Sep  2 23:54:56 PDT 2016
$ LC_TIME=C date
Fri Sep  2 23:54:56 PDT 2016


However, on macOS, I get:

$ LC_TIME=en_CA.UTF-8 date
Fri  2 Sep 2016 23:54:56 PDT
$ LC_TIME=C date
Fri Sep  2 23:54:56 PDT 2016


Note the difference in the output in the en_CA.UTF-8 locale.  More "exotic" locales could produce even wilder output.  I don't recommend parsing the output of date, but if you do, be sure to explicitly state the locale using LC_TIME=C date.

What would be a better approach, then?  The date command's format specifiers are meant for just this kind of thing, and you can get quite close to your desired output.  On GNU/Linux:

$ date +'%a %b %e %Y%n%I:%M %p'
Fri Sep  2 2016
23:54 PM


On macOS:

$ date +'%a %b %e %Y%n%I:%M %p'
Fri Sep  2 2016
23:54 pm


Although the format specifiers are only loosely standardized, I would still consider this to be a more idiomatic and reliable solution than yours.  If you insist on getting exactly the format that you specified in your example, then a bit of post-processing might be needed.

$ date +'%a %b %e %Y%n%I:%M %p' | sed -e 's/  //' -e 's/[Aa][Mm]$/A.M./' -e 's/[Pp][Mm]$/P.M./'