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I have created a shell script as given below.And I need to hide the password, which i will be given when the script prompt for that. If I run the below script written inside the single quotes in my local machine, it will hide the password. But if I add the SSH part it wont.

What should I do for hiding password ?

ssh [email protected] 'echo -n Password:; read -s password; echo; echo $password; '
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3 Answers 3

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5

Try using the -t option to ssh to force tty allocation.

ssh -t [email protected] 'echo -n Password:; read -s password; echo; echo $password;'

EDIT: explanation of suggested solution

If not running a login-session but just a command instead by default SSH won't allocate a pseudo terminal device for the running process. This behavior is not a bug a all, but delibarately chosen by design.

This way it is possible to pass binary data uninterpreted between different machines. Maybe something like:

ssh whoever@wherever 'cat remote_file' | local_program

Passing data between two machines this way would almost be impossible if the data was filtered by a terminal driver in between - Think of the tons of escape sequences you would have to care about !

Without any terminal allocated there is no way of hiding user input. Any attempts to stty something will fail, as there isn't any terminal at all!

To make ssh allocate a pseudo terminal even if not running in a login-session you have to pass the -t parameter to force tty allocation.

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1 Comment

Seems like, I got a hang of what is going on, though a bit. But still the input is useful :-)
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Better use ssh keys, that way, no need to pass a password with the help of a ssh-agent. see a good how-to : https://wiki.archlinux.org/index.php/SSH_Keys

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2 Comments

Actually I just need to hide what i have given.Not specifically for password.If there is an option for entering bank account number and if I want to hid it from others, what should i do for hiding it.
@sputnick: sry, that would be me then. I "downvoted" (nice term I just learned) because the answer while definately a good idea to operate ones ssh passwords/keys it still doesn't fit to the problem described: qerying for any kind of password e-mail file-encryption or whatever. To repeat while sure a pretty perfect solution to the ssh key handling problem I tought the answer might be missleading in respect to the given question.
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I am new to scripts, though I guess this might can help you : 

#!/bin/sh echo -n "Enter Password : " stty -echo read password < /dev/tty stty echo echo echo -n "Enter Password again : " stty -echo read password1 < /dev/tty stty echo echo echo "Password Entered are : $password and $password1"
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3 Comments

IMHO this wont work either as in non-interactive mode there won't be any pseudo terminal allocated on the target machine thus stty and the -s option failing to work.
@mikyra : Wish I really could understand one bit of what you talking about. I am too new to LINUX, so you can guess regarding how new I am to scripts :-). I just learned this thingy few days ago, so I thought might be this would work. I am really not sure, just wanted to give one more option to the OP to look at.
based on the feedback given, I updated the post made above with some kind of rationale. Take a look there if you are still curious.

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