 1. If you want the password prompt to go away then use key based authentication ([described here][1]).

 2. To run commands remotely over ssh you have to give them as an argument to ssh, like the following:


 

&gt; root@host:~ # ssh root@www &#39;ps -ef | grep apache | grep -v grep | wc -l&#39;



  [1]: http://www.cyberciti.biz/tips/ssh-public-key-based-authentication-how-to.html

If you want to continue to use passwords and not use key exchange then you can accomplish this with &#39;expect&#39; like so:

    #!/usr/bin/expect -f
    spawn ssh user@hostname
    expect &quot;password:&quot;
    sleep 1
    send &quot;&lt;your password&gt;\r&quot;
    command1
    command2
    commandN



There&#39;s yet another way to do it using Shared Connections, ie: somebody initiates the connection, using a password, and every subsequent connection will multiplex over the same channel, negating the need for re-authentication. ( And its faster too )


    # ~/.ssh/config 
    ControlMaster auto
    ControlPath ~/.ssh/pool/%r@%h

then you just have to log in, and as long as you are logged in, the bash script will be able to open ssh connections. 

You can then stop your script from working when somebody has not already opened the channel by:

    ssh ... -o KbdInteractiveAuthentication=no ....




If i have in C++ a pointer to a vector:

    vector&lt;int&gt;* vecPtr;

And i&#39;d like to access an element of the vector, then i can do this by dereferncing the vector:

    int a = (*vecPtr)[i];


but will this dereferencing actually create a copy of my vector on the stack? let&#39;s say the vector stores 10000 ints, will by dereferencing the vecPtr 10000 ints be copied?

Thanks!

Dereference vector pointer to access element

I am trying to vocab list for a Greek text we are translating in class. I want to replace every space or tab character with a paragraph mark so that every word appears on its own line. Can anyone give me the sed command, and explain what it is that I&#39;m doing? I’m still trying to figure sed out.

Replace all whitespace with a line break/paragraph mark to make a word list

I am trying to create an ssh connection and do some things on the remote server from within the script.

However the terminal prompts me for a password, then opens the connection in the terminal window instead of the script. The commands don&#39;t get executed until I exit the connection.

How can I ssh from within a bash script?

How to ssh from within a bash script?

I am trying to create an ssh connection and do some things on the remote server from within the script.
However the terminal prompts me for a password, then opens the connection in the terminal window instead of the script. The commands don't get executed until I exit the connection.
How can I ssh from within a bash script?

How can I retrieve a bash variable value if I have the variable name as string? &lt;pre&gt;&lt;code&gt;var1=&quot;this is the real value&quot;
a=&quot;var1&quot;
Do something to get value of var1 just using variable a.
&lt;/code&gt;&lt;/pre&gt;

### Context:

I have some AMI&#39;s ([Amazon Machine Image][1]) and I want to fire up a few instances of each AMI. As soon as they finish booting, I want to setup each instance according to its AMI type. I don&#39;t want to bake lots of scripts or secret keys inside any AMI so I prepared a generalized startup script and I put it on [S3][2] with a publicly accessible link. In rc.local I put small piece of code which fetches the startup script and executes it. This is all I have in the AMIs. Then each AMI accesses a common configuration script which is applicable to all AMIs and special setup scripts for each. These scripts are private and require a signed URL to access them.

So now, when I fire an instance of an AMI (my\_private\_ami\_1), I pass a signed URL for one more file presented on S3 which contains signed URL for all private scripts in terms of key/value pair.&lt;pre&gt;&lt;code&gt;config\_url=&quot;http://s3.amazo.../config?signature&quot;
my\_private\_ami\_1=&quot;http://s3.amazo.../ami\_1?signature&quot;
...
&lt;/code&gt;&lt;/pre&gt;
When the startup script runs, it downloads the above file and &lt;code&gt;source&lt;/code&gt;&#39;s it. Then it checks for its AMI type and picks the correct setup script for itself.
&lt;pre&gt;&lt;code&gt;ami\_type=GET AMI TYPE #ex: sets ami\_type to my\_private\_ami\_1
setup\_url=GET THE SETUP FILE URL BASED ON AMI\_TYPE # this is where this problem arises
&lt;/code&gt;&lt;/pre&gt;
So now I can have a generic code which can fire instances irrespective of their AMI types and instances can take care of themselves.

  [1]: http://aws.amazon.com/ec2/
  [2]: http://aws.amazon.com/s3

How to get a variable value if variable name is stored as string?

Is there a way to do something like PHPs `$array[] = &#39;foo&#39;;` in bash vs doing:

    array[0]=&#39;foo&#39;
    array[1]=&#39;bar&#39;

Add a new element to an array without specifying the index in Bash

Does exist in linux bash something similar to the following code in PHP:

    list($var1, $var2, $var3) = function_that_returns_a_three_element_array() ;

i.e. you assign in one sentence a corresponding value to 3 different variables.

Let&#39;s say I have the bash function `myBashFuntion` that writes to stdout the string &quot;qwert asdfg zxcvb&quot;.
Is it possible to do something like:

    (var1 var2 var3) = ( `myBashFuntion param1 param2` )

The part at the left of the equal sign is not valid syntax of course. I&#39;m just trying to explain what I&#39;m asking for.

What does work, though, is the following:

    array = ( `myBashFuntion param1 param2` )
    echo ${array[0]} ${array[1]} ${array[2]}

But an indexed array is not as descriptive as plain variable names.  
However, I could just do:

    var1 = ${array[0]} ; var2 = ${array[1]} ; var3 = ${array[2]}

But those are 3 more statements that I&#39;d prefer to avoid.

I&#39;m just looking for a shortcut syntax. Is it possible?

Linux bash: Multiple variable assignment

I&#39;m trying to parse JSON returned from a curl request, like so:

    curl &#39;http://twitter.com/users/username.json&#39; |
        sed -e &#39;s/[{}]/&#39;&#39;/g&#39; | 
        awk -v k=&quot;text&quot; &#39;{n=split($0,a,&quot;,&quot;); for (i=1; i&lt;=n; i++) print a[i]}&#39;

The above splits the JSON into fields, for example:
    
    % ...
    &quot;geo_enabled&quot;:false
    &quot;friends_count&quot;:245
    &quot;profile_text_color&quot;:&quot;000000&quot;
    &quot;status&quot;:&quot;in_reply_to_screen_name&quot;:null
    &quot;source&quot;:&quot;web&quot;
    &quot;truncated&quot;:false
    &quot;text&quot;:&quot;My status&quot;
    &quot;favorited&quot;:false
    % ...

How do I print a specific field (denoted by the `-v k=text`)?

Parsing JSON with Unix tools

&gt; **Possible Duplicate:**  
&gt; [rename multiple files at once in unix](https://stackoverflow.com/questions/1086502/rename-multiple-files-at-once-in-unix)  

I would like to rename all files from a folder using a regex (add a name to the end of name) and move to another folder. 

It my opinion, it should be looking like this:

    mv -v ./images/*.png ./test/*test.png

but it does not work.

Can anyone suggest me a solution?


Rename files using a regex with bash

I know the answer is out there, but I&#39;m pretty Unix-dumb and probably wouldn&#39;t recognize the solution if it hit me in the face.

I&#39;m on a Mac, connecting to a SVN server via SSH tunneling.  I have to `ssh-add privateKey.txt` every time I want to connect to the SVN server (Both Cornerstone and Xcode are connecting to SVN).  

Is there a way to &quot;save&quot; the key somewhere so I don&#39;t have to do this every time?  Add it to my Keychain? Some config file? Start up script? 

SVN+SSH, not having to do ssh-add every time? (Mac OS)

How can I connect to remote MySQL database through SSH from java application? Small code example is helpful for me and I&#39;d appreciate this.

Connect to remote MySQL database through SSH using Java

I&#39;m trying to use [Jsch][1] to establish an SSH connection in Java. My code produces the following exception:

    com.jcraft.jsch.JSchException: UnknownHostKey: mywebsite.com. 
    RSA key fingerprint is 22:fb:ee:fe:18:cd:aa:9a:9c:78:89:9f:b4:78:75:b4

I cannot find how to verify the host key in the Jsch documentation. I have included my code below.

    import com.jcraft.jsch.JSch;
    import com.jcraft.jsch.Session;
    
    public class ssh {
        public static void main(String[] arg) {
        
    	    try {
                JSch jsch = new JSch();
    
                //create SSH connection
                String host = &quot;mywebsite.com&quot;;
                String user = &quot;username&quot;;
                String password = &quot;123456&quot;;
           
                Session session = jsch.getSession(user, host, 22);
                session.setPassword(password);
                session.connect();
    
            } catch(Exception e) {
                System.out.println(e);
    	    } 
        }
    }


   [1]: http://www.jcraft.com/jsch/

com.jcraft.jsch.JSchException: UnknownHostKey

I want to open a file inside Emacs which is located on a remote server, with sudo powers on the server. I can open local files with sudo via Tramp like this:

    C-x C-f /sudo::/home/user/file

But I want to use sudo on the server:

    C-x C-f /sudo::user@server/home/user/file

But this gives me sudo powers on my local machine, it asks for my sudo password on the local machine. Is there a way to use sudo on the server?

BTW: Emacs is not installed on the server

Open file via SSH and Sudo with Emacs

On Cygwin, I want a Bash script to:

1. Create an SSH tunnel to a remote server. 
2. Do some work locally that uses the tunnel. 
3. Then shut down the tunnel.

The shutdown part has me perplexed.

Currently, I have a lame solution. In one shell I run the following to create a tunnel:

    # Create the tunnel - this works! It runs forever, until the shell is quit.
    ssh -nNT -L 50000:localhost:3306 jm@sampledomain.com

Then, in another shell window, I do my work:
    
    # Do some MySQL stuff over local port 50000 (which goes to remote port 3306)

Finally, when I am done, I close the first shell window to kill the tunnel.

I&#39;d like to do this all in one script like:

    # Create tunnel
    # Do work
    # Kill tunnel

How do I keep track of the tunnel process, so I know which one to kill?

Content Type	Original Author	Original Content on Stackoverflow
Question	Andrew	View Question on Stackoverflow
Solution 1 - Bash	halfdan	View Answer on Stackoverflow
Solution 2 - Bash	SiegeX	View Answer on Stackoverflow
Solution 3 - Bash	Kent Fredric	View Answer on Stackoverflow

How to ssh from within a bash script?

Bash Problem Overview

Bash Solutions

Solution 1 - Bash

Solution 2 - Bash

Solution 3 - Bash

Replace all whitespace with a line break/paragraph mark to make a word list

Dereference vector pointer to access element

Attributions