[linux] How can I get the current date and time in the terminal and set a custom command in the terminal for it?

I have to check the time in a Linux terminal.

What is the command for getting date and time in a Linux terminal?

Is there a way in which we can set a custom function?

You can use date to get time and date of a day:

[pengyu@GLaDOS ~]$date
Tue Aug 27 15:01:27 CST 2013

Also hwclock would do:

[pengyu@GLaDOS ~]$hwclock
Tue 27 Aug 2013 03:01:29 PM CST  -0.516080 seconds

For customized output, you can either redirect the output of date to something like awk, or write your own program to do that.

Remember to put your own executable scripts/binary into your PATH (e.g. /usr/bin) to make it invokable anywhere.