Change password in headless mode

I am building a script to fully automate a VPS setup, and I need to change the root password. I would like to avoid typing it as the script is running through SSH.

Is there a way to redirect an arbitrary value to the input of passwd command?

EDIT

I know for passwd < passwd_file.txt containing the password twice... I would like to know if there is a more elegant way as it seems a little bit clumsy to use a temp file for this purpose.

edited Apr 28 '12 at 16:12

Caleb

50.3k9146191

asked Apr 13 '12 at 16:46

Mike Aski

12318

Why not just set a disabled password usermod -p '*' root, and setup SSH key-based authentication?
– Zoredache
Apr 13 '12 at 18:16

I would like to keep a (strong) password to be able to log from another user.
– Mike Aski
Apr 14 '12 at 5:45

expect also works for may things
– RobotHumans
Apr 14 '12 at 6:06

I finally found the solution: see below...
– Mike Aski
Apr 14 '12 at 6:07

add a comment |

I am building a script to fully automate a VPS setup, and I need to change the root password. I would like to avoid typing it as the script is running through SSH.

Is there a way to redirect an arbitrary value to the input of passwd command?

EDIT

I know for passwd < passwd_file.txt containing the password twice... I would like to know if there is a more elegant way as it seems a little bit clumsy to use a temp file for this purpose.

edited Apr 28 '12 at 16:12

Caleb

50.3k9146191

asked Apr 13 '12 at 16:46

Mike Aski

12318

Why not just set a disabled password usermod -p '*' root, and setup SSH key-based authentication?
– Zoredache
Apr 13 '12 at 18:16

I would like to keep a (strong) password to be able to log from another user.
– Mike Aski
Apr 14 '12 at 5:45

expect also works for may things
– RobotHumans
Apr 14 '12 at 6:06

I finally found the solution: see below...
– Mike Aski
Apr 14 '12 at 6:07

add a comment |

I am building a script to fully automate a VPS setup, and I need to change the root password. I would like to avoid typing it as the script is running through SSH.

Is there a way to redirect an arbitrary value to the input of passwd command?

EDIT

I know for passwd < passwd_file.txt containing the password twice... I would like to know if there is a more elegant way as it seems a little bit clumsy to use a temp file for this purpose.

edited Apr 28 '12 at 16:12

Caleb

50.3k9146191

asked Apr 13 '12 at 16:46

Mike Aski

12318

I am building a script to fully automate a VPS setup, and I need to change the root password. I would like to avoid typing it as the script is running through SSH.

Is there a way to redirect an arbitrary value to the input of passwd command?

EDIT

I know for passwd < passwd_file.txt containing the password twice... I would like to know if there is a more elegant way as it seems a little bit clumsy to use a temp file for this purpose.

shell ubuntu io-redirection password

edited Apr 28 '12 at 16:12

Caleb

50.3k9146191

asked Apr 13 '12 at 16:46

Mike Aski

12318

edited Apr 28 '12 at 16:12

Caleb

50.3k9146191

asked Apr 13 '12 at 16:46

Mike Aski

12318

edited Apr 28 '12 at 16:12

Caleb

50.3k9146191

edited Apr 28 '12 at 16:12

Caleb

50.3k9146191

edited Apr 28 '12 at 16:12

Caleb

50.3k9146191

asked Apr 13 '12 at 16:46

Mike Aski

12318

asked Apr 13 '12 at 16:46

Mike Aski

12318

asked Apr 13 '12 at 16:46

Mike Aski

12318

Why not just set a disabled password usermod -p '*' root, and setup SSH key-based authentication?
– Zoredache
Apr 13 '12 at 18:16

I would like to keep a (strong) password to be able to log from another user.
– Mike Aski
Apr 14 '12 at 5:45

expect also works for may things
– RobotHumans
Apr 14 '12 at 6:06

I finally found the solution: see below...
– Mike Aski
Apr 14 '12 at 6:07

add a comment |

Why not just set a disabled password usermod -p '*' root, and setup SSH key-based authentication?
– Zoredache
Apr 13 '12 at 18:16

I would like to keep a (strong) password to be able to log from another user.
– Mike Aski
Apr 14 '12 at 5:45

expect also works for may things
– RobotHumans
Apr 14 '12 at 6:06

I finally found the solution: see below...
– Mike Aski
Apr 14 '12 at 6:07

Why not just set a disabled password usermod -p '*' root, and setup SSH key-based authentication?
– Zoredache
Apr 13 '12 at 18:16

I would like to keep a (strong) password to be able to log from another user.
– Mike Aski
Apr 14 '12 at 5:45

expect also works for may things
– RobotHumans
Apr 14 '12 at 6:06

I finally found the solution: see below...
– Mike Aski
Apr 14 '12 at 6:07

add a comment |

4 Answers
4

active

oldest

votes

You don't say what version of UNIX you're using, but on Linux the passwd(1) man page shows:

   --stdin

          This option is used to indicate that passwd should read the  new

          password from standard input, which can be a pipe.

So all you have to do is run:

echo 'somepassword' | passwd --stdin

Edit to add: more portable is chpasswd which exists on (at least) both Red Hat and Ubuntu:

echo 'someuser:somepassword' | chpasswd

See the man page.

edited Apr 28 '12 at 15:35

answered Apr 13 '12 at 19:32

MadScientist

1,92811316

I would have been really fond of this option, but it does not exists on Ubuntu... :-(
– Mike Aski
Apr 14 '12 at 5:47

You can use chpasswd. That exists on both Red Hat and Ubuntu.
– MadScientist
Apr 28 '12 at 15:33

add a comment |

I think you'll have a tough time doing what you want. The passwd command goes to great lengths to avoid just the situation you describe, so as to hinder any password guessing schemes, and circumvent a lot of potential security problems.

Can you use the useradd command? Typical linux useradd has a "-p" or "--password" option that lets you set the encrypted password to some value. You can get that encrypted password out of the file /etc/shadow.

The other option is to monkey with the file /etc/shadow. It shouldn't be too hard to used sed or something to change the salted, encrypted root password.

answered Apr 13 '12 at 16:52

Bruce Ediger

34.7k566119

First, thanks for your quick reply. But useradd is not recommended, man pages says I should prefer adduser... And second option is yet worst than mine... ;-P
– Mike Aski
Apr 13 '12 at 16:53

1

@MikeAski, On many systems adduser is simply a front-end to useradd. For general interactive usage, the adduser command is preferred since it usually has a number of useful defaults. From a script useradd, or in this case usermod is potentially a valid choice.
– Zoredache
Apr 13 '12 at 18:15

add a comment |

Yes! Found the way. printf saved me:

HOST=...

echo "Root password? " && read -r ROOT_PASSWORD

...

ssh root@$HOST <<EOF

    printf "$ROOT_PASSWORDn$ROOT_PASSWORDn" | passwd

EOF

That is to me the best way out: clean & perfectly secure as password never get on local nether remote host in clear (through ssh connection only).

answered Apr 14 '12 at 6:06

Mike Aski

12318

add a comment |

You could wrap tmux around passwd:

tmux new-session -ds chpwd passwd

tmux send-keys -t chpwd NEWPASSWORD$'n'

tmux send-keys -t chpwd NEWPASSWORD$'n'

Run as root of course.

answered Apr 13 '12 at 17:25

Thor

11.6k13358

add a comment |

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4 Answers
4

active

oldest

votes

4 Answers
4

active

oldest

votes

You don't say what version of UNIX you're using, but on Linux the passwd(1) man page shows:

   --stdin

          This option is used to indicate that passwd should read the  new

          password from standard input, which can be a pipe.

So all you have to do is run:

echo 'somepassword' | passwd --stdin

Edit to add: more portable is chpasswd which exists on (at least) both Red Hat and Ubuntu:

echo 'someuser:somepassword' | chpasswd

See the man page.

edited Apr 28 '12 at 15:35

answered Apr 13 '12 at 19:32

MadScientist

1,92811316

I would have been really fond of this option, but it does not exists on Ubuntu... :-(
– Mike Aski
Apr 14 '12 at 5:47

You can use chpasswd. That exists on both Red Hat and Ubuntu.
– MadScientist
Apr 28 '12 at 15:33

add a comment |

You don't say what version of UNIX you're using, but on Linux the passwd(1) man page shows:

   --stdin

          This option is used to indicate that passwd should read the  new

          password from standard input, which can be a pipe.

So all you have to do is run:

echo 'somepassword' | passwd --stdin

Edit to add: more portable is chpasswd which exists on (at least) both Red Hat and Ubuntu:

echo 'someuser:somepassword' | chpasswd

See the man page.

edited Apr 28 '12 at 15:35

answered Apr 13 '12 at 19:32

MadScientist

1,92811316

I would have been really fond of this option, but it does not exists on Ubuntu... :-(
– Mike Aski
Apr 14 '12 at 5:47

You can use chpasswd. That exists on both Red Hat and Ubuntu.
– MadScientist
Apr 28 '12 at 15:33

add a comment |

You don't say what version of UNIX you're using, but on Linux the passwd(1) man page shows:

   --stdin

          This option is used to indicate that passwd should read the  new

          password from standard input, which can be a pipe.

So all you have to do is run:

echo 'somepassword' | passwd --stdin

Edit to add: more portable is chpasswd which exists on (at least) both Red Hat and Ubuntu:

echo 'someuser:somepassword' | chpasswd

See the man page.

edited Apr 28 '12 at 15:35

answered Apr 13 '12 at 19:32

MadScientist

1,92811316

You don't say what version of UNIX you're using, but on Linux the passwd(1) man page shows:

   --stdin

          This option is used to indicate that passwd should read the  new

          password from standard input, which can be a pipe.

So all you have to do is run:

echo 'somepassword' | passwd --stdin

Edit to add: more portable is chpasswd which exists on (at least) both Red Hat and Ubuntu:

echo 'someuser:somepassword' | chpasswd

See the man page.

edited Apr 28 '12 at 15:35

answered Apr 13 '12 at 19:32

MadScientist

1,92811316

edited Apr 28 '12 at 15:35

answered Apr 13 '12 at 19:32

MadScientist

1,92811316

answered Apr 13 '12 at 19:32

MadScientist

1,92811316

answered Apr 13 '12 at 19:32

MadScientist

1,92811316

I would have been really fond of this option, but it does not exists on Ubuntu... :-(
– Mike Aski
Apr 14 '12 at 5:47

You can use chpasswd. That exists on both Red Hat and Ubuntu.
– MadScientist
Apr 28 '12 at 15:33

add a comment |

I would have been really fond of this option, but it does not exists on Ubuntu... :-(
– Mike Aski
Apr 14 '12 at 5:47

You can use chpasswd. That exists on both Red Hat and Ubuntu.
– MadScientist
Apr 28 '12 at 15:33

I would have been really fond of this option, but it does not exists on Ubuntu... :-(
– Mike Aski
Apr 14 '12 at 5:47

You can use chpasswd. That exists on both Red Hat and Ubuntu.
– MadScientist
Apr 28 '12 at 15:33

add a comment |

The other option is to monkey with the file /etc/shadow. It shouldn't be too hard to used sed or something to change the salted, encrypted root password.

answered Apr 13 '12 at 16:52

Bruce Ediger

34.7k566119

First, thanks for your quick reply. But useradd is not recommended, man pages says I should prefer adduser... And second option is yet worst than mine... ;-P
– Mike Aski
Apr 13 '12 at 16:53

1

@MikeAski, On many systems adduser is simply a front-end to useradd. For general interactive usage, the adduser command is preferred since it usually has a number of useful defaults. From a script useradd, or in this case usermod is potentially a valid choice.
– Zoredache
Apr 13 '12 at 18:15

add a comment |

The other option is to monkey with the file /etc/shadow. It shouldn't be too hard to used sed or something to change the salted, encrypted root password.

answered Apr 13 '12 at 16:52

Bruce Ediger

34.7k566119

First, thanks for your quick reply. But useradd is not recommended, man pages says I should prefer adduser... And second option is yet worst than mine... ;-P
– Mike Aski
Apr 13 '12 at 16:53

1

@MikeAski, On many systems adduser is simply a front-end to useradd. For general interactive usage, the adduser command is preferred since it usually has a number of useful defaults. From a script useradd, or in this case usermod is potentially a valid choice.
– Zoredache
Apr 13 '12 at 18:15

add a comment |

The other option is to monkey with the file /etc/shadow. It shouldn't be too hard to used sed or something to change the salted, encrypted root password.

answered Apr 13 '12 at 16:52

Bruce Ediger

34.7k566119

The other option is to monkey with the file /etc/shadow. It shouldn't be too hard to used sed or something to change the salted, encrypted root password.

answered Apr 13 '12 at 16:52

Bruce Ediger

34.7k566119

answered Apr 13 '12 at 16:52

Bruce Ediger

34.7k566119

answered Apr 13 '12 at 16:52

Bruce Ediger

34.7k566119

answered Apr 13 '12 at 16:52

Bruce Ediger

34.7k566119

First, thanks for your quick reply. But useradd is not recommended, man pages says I should prefer adduser... And second option is yet worst than mine... ;-P
– Mike Aski
Apr 13 '12 at 16:53

1

@MikeAski, On many systems adduser is simply a front-end to useradd. For general interactive usage, the adduser command is preferred since it usually has a number of useful defaults. From a script useradd, or in this case usermod is potentially a valid choice.
– Zoredache
Apr 13 '12 at 18:15

add a comment |

First, thanks for your quick reply. But useradd is not recommended, man pages says I should prefer adduser... And second option is yet worst than mine... ;-P
– Mike Aski
Apr 13 '12 at 16:53

1

@MikeAski, On many systems adduser is simply a front-end to useradd. For general interactive usage, the adduser command is preferred since it usually has a number of useful defaults. From a script useradd, or in this case usermod is potentially a valid choice.
– Zoredache
Apr 13 '12 at 18:15

First, thanks for your quick reply. But useradd is not recommended, man pages says I should prefer adduser... And second option is yet worst than mine... ;-P
– Mike Aski
Apr 13 '12 at 16:53

@MikeAski, On many systems adduser is simply a front-end to useradd. For general interactive usage, the adduser command is preferred since it usually has a number of useful defaults. From a script useradd, or in this case usermod is potentially a valid choice.
– Zoredache
Apr 13 '12 at 18:15

add a comment |

Yes! Found the way. printf saved me:

HOST=...

echo "Root password? " && read -r ROOT_PASSWORD

...

ssh root@$HOST <<EOF

    printf "$ROOT_PASSWORDn$ROOT_PASSWORDn" | passwd

EOF

That is to me the best way out: clean & perfectly secure as password never get on local nether remote host in clear (through ssh connection only).

answered Apr 14 '12 at 6:06

Mike Aski

12318

add a comment |

Yes! Found the way. printf saved me:

HOST=...

echo "Root password? " && read -r ROOT_PASSWORD

...

ssh root@$HOST <<EOF

    printf "$ROOT_PASSWORDn$ROOT_PASSWORDn" | passwd

EOF

That is to me the best way out: clean & perfectly secure as password never get on local nether remote host in clear (through ssh connection only).

answered Apr 14 '12 at 6:06

Mike Aski

12318

add a comment |

Yes! Found the way. printf saved me:

HOST=...

echo "Root password? " && read -r ROOT_PASSWORD

...

ssh root@$HOST <<EOF

    printf "$ROOT_PASSWORDn$ROOT_PASSWORDn" | passwd

EOF

That is to me the best way out: clean & perfectly secure as password never get on local nether remote host in clear (through ssh connection only).

answered Apr 14 '12 at 6:06

Mike Aski

12318

Yes! Found the way. printf saved me:

HOST=...

echo "Root password? " && read -r ROOT_PASSWORD

...

ssh root@$HOST <<EOF

    printf "$ROOT_PASSWORDn$ROOT_PASSWORDn" | passwd

EOF

That is to me the best way out: clean & perfectly secure as password never get on local nether remote host in clear (through ssh connection only).

answered Apr 14 '12 at 6:06

Mike Aski

12318

answered Apr 14 '12 at 6:06

Mike Aski

12318

answered Apr 14 '12 at 6:06

Mike Aski

12318

answered Apr 14 '12 at 6:06

Mike Aski

12318

add a comment |

You could wrap tmux around passwd:

tmux new-session -ds chpwd passwd

tmux send-keys -t chpwd NEWPASSWORD$'n'

tmux send-keys -t chpwd NEWPASSWORD$'n'

Run as root of course.

answered Apr 13 '12 at 17:25

Thor

11.6k13358

add a comment |

You could wrap tmux around passwd:

tmux new-session -ds chpwd passwd

tmux send-keys -t chpwd NEWPASSWORD$'n'

tmux send-keys -t chpwd NEWPASSWORD$'n'

Run as root of course.

answered Apr 13 '12 at 17:25

Thor

11.6k13358

add a comment |

You could wrap tmux around passwd:

tmux new-session -ds chpwd passwd

tmux send-keys -t chpwd NEWPASSWORD$'n'

tmux send-keys -t chpwd NEWPASSWORD$'n'

Run as root of course.

answered Apr 13 '12 at 17:25

Thor

11.6k13358

You could wrap tmux around passwd:

tmux new-session -ds chpwd passwd

tmux send-keys -t chpwd NEWPASSWORD$'n'

tmux send-keys -t chpwd NEWPASSWORD$'n'

Run as root of course.

answered Apr 13 '12 at 17:25

Thor

11.6k13358

answered Apr 13 '12 at 17:25

Thor

11.6k13358

answered Apr 13 '12 at 17:25

Thor

11.6k13358

answered Apr 13 '12 at 17:25

Thor

11.6k13358

add a comment |

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