How do I get the password from the su command?

Question

I am copying files from a remote server to my local server. Here is the code that does this:

ssh -q username@$192.168.162.156 "su -lc 'cp /copy/from /copy/it/here'"

I am using this code segment in a for loop so it will prompt for a password for every iteration. How do I get the password from the su command? (without using rsync or sudo). I also don't want any alternatives even if they are better.

Do you really need the `su` command? Can't you just copy the files like: `ssh @ cat // > ` — Cyclonecode, Jun 04 '14 at 15:01
I'd expect `expect` to solve this. So many threads already about this. Try to search for `ssh expect`. — konsolebox, Jun 04 '14 at 15:02

phoxis · Answer 1 · 2014-06-04T15:04:39.557

2

Execute in local server:

scp remote_user@remote_server:/path/to/files /dir/to/copy

When executed in local machine, this logon to remote_server as user remote_user and copy the files in /path/to/files/ in remote server to /dir/to/copy/ in local server.

You might want to setup a passwordless ssh connection to run it in a script which requires no passwords.

Read man scp for more.

edited Jun 04 '14 at 15:04

answered Jun 04 '14 at 14:58

phoxis

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score 0 · Answer 2 · answered Jun 04 '14 at 15:00

0

You can pass the password via stdin:

echo 'password' | su -c [...]

answered Jun 04 '14 at 15:00

Eun

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This will fortunately not work, because it is insecure. – hek2mgl Jun 04 '14 at 15:01
Obtaining the password from `su` would be insecure too (but fortunately cannot be done). – tripleee Jun 04 '14 at 15:21

score 0 · Answer 3 · answered May 13 '15 at 10:41

If repetitive promt for password is your problem, you may try

Create passwordless ssh setup between host
Use new ssh module of perl
Tar all you files and then send it over network. This way only one tar file is send and password prompt will only be for once.

How do I get the password from the su command?

3 Answers3