How do I generate random passwords under Linux / UNIX / Mac OS X and *BSD operating systems?

You can use the following command to generate the random password:

tr -dc A-Za-z0-9_ < /dev/urandom | head -c 16 | xargs

Sample outputs:

1z2G4SVmZOdd4uK4

You can create a bash shell function as follows (add to your ~/.bashrc):

genpasswd() { 
	local l=$1
       	[ "$l" == "" ] && l=16
      	tr -dc A-Za-z0-9_ < /dev/urandom | head -c ${l} | xargs 
}

Now use genpasswd as follows to create 8 character long password:
genpasswd 8
Sample outputs:

Es5Yzf8H

See also:

• Linux / UNIX: Generating random password with mkpasswd