linux - Command to change the default home directory of a user
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Ibrahim's comment on the other answer is the correct way to alter an existing user's home directory. 
Change the user's home directory:
usermod -d /newhome/username username

usermod is the command to edit an existing user. 
-d (abbreviation for --home) will change the user's home directory.

Change the user's home directory + Move the contents of the user's current directory:
usermod -m -d /newhome/username username

-m (abbreviation for --move-home) will move the content from the user's current directory to the new directory.
