Use `ftp` to obtain source code.

I am following a linux command line book to learning compiling.

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	[me@linuxbox src]$ ftp ftp.gnu.org 
	Connected to ftp.gnu.org. 
	220 GNU FTP server ready.

I tried and it reported an error

	$ ftp ftp://ftp.gnu.org/
	-bash: ftp: command not found

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	$ ftp 
	-bash: ftp: command not found

How to solve the problem?