How to use SSH to run a local shell script on a remote machine?

Question

If Machine A is a Windows box, you can use Plink (part of PuTTY) with the -m parameter, and it will execute the local script on the remote server.

plink root@MachineB -m local_script.sh

If Machine A is a Unix-based system, you can use:

ssh root@MachineB 'bash -s' < local_script.sh

You shouldn't have to copy the script to the remote server to run it.

This is an old question, and Jason's answer works fine, but I would like to add this:

ssh user@host <<'ENDSSH'
#commands to run on remote host
ENDSSH

This can also be used with su and commands which require user input. (note the ' escaped heredoc)

Edit: Since this answer keeps getting bits of traffic, i would add even more info to this wonderful use of heredoc:

You can nest commands with this syntax, and thats the only way nesting seems to work (in a sane way)

ssh user@host <<'ENDSSH'
#commands to run on remote host
ssh user@host2 <<'END2'
# Another bunch of commands on another host
wall <<'ENDWALL'
Error: Out of cheese
ENDWALL
ftp ftp.secureftp-test.com <<'ENDFTP'
test
test
ls
ENDFTP
END2
ENDSSH

You can actually have a conversation with some services like telnet, ftp, etc. But remember that heredoc just sends the stdin as text, it doesn't wait for response between lines

Edit: I just found out that you can indent the insides with tabs if you use <<-END !

ssh user@host <<-'ENDSSH'
    #commands to run on remote host
    ssh user@host2 <<-'END2'
        # Another bunch of commands on another host
        wall <<-'ENDWALL'
            Error: Out of cheese
        ENDWALL
        ftp ftp.secureftp-test.com <<-'ENDFTP'
            test
            test
            ls
        ENDFTP
    END2
ENDSSH

(I think this should work)

Also see http://tldp.org/LDP/abs/html/here-docs.html

Also, don't forget to escape variables if you want to pick them up from the destination host.

This has caught me out in the past.

For example:

user@host> ssh user2@host2 "echo \$HOME"

prints out /home/user2

while

user@host> ssh user2@host2 "echo $HOME"

prints out /home/user

Another example:

user@host> ssh user2@host2 "echo hello world | awk '{print \$1}'"

prints out "hello" correctly.

This is an extension to YarekT's answer to combine inline remote commands with passing ENV variables from the local machine to the remote host so you can parameterize your scripts on the remote side:

ssh user@host ARG1=$ARG1 ARG2=$ARG2 'bash -s' <<'ENDSSH'
  # commands to run on remote host
  echo $ARG1 $ARG2
ENDSSH

I found this exceptionally helpful by keeping it all in one script so it's very readable and maintainable.

Why this works. ssh supports the following syntax:

ssh user@host remote_command

In bash we can specify environment variables to define prior to running a command on a single line like so:

ENV_VAR_1='value1' ENV_VAR_2='value2' bash -c 'echo $ENV_VAR_1 $ENV_VAR_2'

That makes it easy to define variables prior to running a command. In this case echo is our command we're running. Everything before echo defines environment variables.

So we combine those two features and YarekT's answer to get:

ssh user@host ARG1=$ARG1 ARG2=$ARG2 'bash -s' <<'ENDSSH'...

In this case we are setting ARG1 and ARG2 to local values. Sending everything after user@host as the remote_command. When the remote machine executes the command ARG1 and ARG2 are set the local values, thanks to local command line evaluation, which defines environment variables on the remote server, then executes the bash -s command using those variables. Voila.

<hostA_shell_prompt>$ ssh user@hostB "ls -la"

That will prompt you for password, unless you have copied your hostA user's public key to the authorized_keys file on the home of user .ssh's directory. That will allow for passwordless authentication (if accepted as an auth method on the ssh server's configuration)

I've started using Fabric for more sophisticated operations. Fabric requires Python and a couple of other dependencies, but only on the client machine. The server need only be a ssh server. I find this tool to be much more powerful than shell scripts handed off to SSH, and well worth the trouble of getting set up (particularly if you enjoy programming in Python). Fabric handles running scripts on multiple hosts (or hosts of certain roles), helps facilitate idempotent operations (such as adding a line to a config script, but not if it's already there), and allows construction of more complex logic (such as the Python language can provide).