How to create a shell script to change the password without prompt?

Question

I wanted to vary my password in my Unix user using the shell script, but without being prompted to enter the old password.

That means i would like to supply the old and new password in my shell script itself, such during the prompt it'll read it from the script file.

Answer 1

Use the below command: 

$> echo -e -n "oldpasswd\nnewpasswd\nnewpasswd" | passwd

Or you can write the file with your passwords

oldpassword

newpassword

newpassword

and use the following command: $> passwd < file

The pipe and redirection operators are replacing the quality input with either the content of the file redirected, either the output of the command piped.

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