time=$(date “+%Y%m%d-%H%M%S”)

or

time=$(date “+%Y-%m-%d %H:%M:%S”)

……

in any format you want

echo “${time}”

the above two lines of simple code is that the shell takes the current time and outputs it in the format it wants.

a couple of things to note

1. date is followed by a space, otherwise the command cannot be recognized, the shell is very strict with the space.
2. Y shows 4-digit years, such as: 2018; Y displays a 2-digit year, such as: 18. M is for month; M is for minutes. D represents the day, and D represents the current date, i.e. 1/18/18(i.e. 2018.1.18). H represents hours, and H shows months (somewhat muddled). S displays the current second in milliseconds; S displays the current second in seconds.