A bunch of Unix date scripting things

Unix shell scripting is not one of my better-know areas of programming, but it’s on my list of things to learn. Some interesting bits about the date function.¹

1. Want the long date, like Thursday, January 28, 2021? → date +"%A, %B %d, %Y"
2. Want something like the above but with abbreviated month Thursday, Jan 28, 2021? → date +"%A, %b %d, %Y"
3. Time zone in the format of "-05:00" on macOS is:

#!/bin/bash

tz=$(date +"%z" | sd '(\d{2})(\d{2})' '$1:$2')
echo $tz

4. Long date in the format of 2021-01-28T05:30:48-05:00 that is use by Hugo²:

tz=$(date +"%z" | sd '(\d{2})(\d{2})' '$1:$2')
md_date=`date +"%Y-%m-%dT%H:%M:%S"`

5. Speaking of dates, this reference has very detailed information on date and time in the Unix shell.
6. Date in the format of 2021-01-28 is date +"%Y-%m-%d"

Unix slurp command output into a variable

In the UNIX shell, slurping the output of the command into a variable is done this way:³

OUTPUT=$(ls -1)
echo "${OUTPUT}"

MULTILINE=$(ls \
   -1)
echo "${MULTILINE}"

Append or overwrite a file in Unix shell

You can either append to a file or overwrite the contents from the shell.⁴

To append to a file, it’s echo "hello" >> file.txt whereas to overwrite the contents of a file, it’s echo "hello" > file.txt

no way