[bash] YYYY-MM-DD format date in shell script

I tried using $(date) in my bash shell script, however, I want the date in YYYY-MM-DD format.
How do I get this?

You're looking for ISO 8601 standard date format, so if you have GNU date (or any date command more modern than 1988) just do: $(date -I)

#!/bin/bash -e

x='2018-01-18 10:00:00'
a=$(date -d "$x")
b=$(date -d "$a 10 min" "+%Y-%m-%d %H:%M:%S")
c=$(date -d "$b 10 min" "+%Y-%m-%d %H:%M:%S")
#date -d "$a 30 min" "+%Y-%m-%d %H:%M:%S"

echo Entered Date is $x
echo Second Date is $b
echo Third Date is $c

Here x is sample date used & then example displays both formatting of data as well as getting dates 10 mins more then current date.

Try to use this command :

date | cut -d " " -f2-4 | tr " " "-" 

The output would be like: 21-Feb-2021

I use the following formulation:

TODAY=`date -I`
echo $TODAY

Checkout the man page for date, there is a number of other useful options:

man date

date -d '1 hour ago' '+%Y-%m-%d'

The output would be 2015-06-14.

I use $(date +"%Y-%m-%d") or $(date +"%Y-%m-%d %T") with time and hours.

if you want the year in a two number format such as 17 rather than 2017, do the following:

DATE=`date +%d-%m-%y`

$(date +%F_%H-%M-%S)

can be used to remove colons (:) in between

output

2018-06-20_09-55-58

With recent Bash (version = 4.2), you can use the builtin printf with the format modifier %(strftime_format)T:

$ printf '%(%Y-%m-%d)T\n' -1  # Get YYYY-MM-DD (-1 stands for "current time")
2017-11-10
$ printf '%(%F)T\n' -1  # Synonym of the above
2017-11-10
$ printf -v date '%(%F)T' -1  # Capture as var $date

printf is much faster than date since it's a Bash builtin while date is an external command.

As well, printf -v date ... is faster than date=$(printf ...) since it doesn't require forking a subshell.

Whenever I have a task like this I end up falling back to

$ man strftime

to remind myself of all the possibilities for time formatting options.

You can set date as environment variable and later u can use it

setenv DATE `date "+%Y-%m-%d"`
echo "----------- ${DATE} -------------"

or

DATE =`date "+%Y-%m-%d"`
echo "----------- ${DATE} -------------"

Try: $(date +%F)

You can do something like this:

$ date +'%Y-%m-%d'