Linux bash ssh command

SSH: Execute Remote Command or Script – Linux

This is quite a common task for Linux system administrators, when it is needed to execute some command or a local Bash script from a one Linux workstation or a server on another remote Linux machine over SSH.

In this article you will find the examples of how to execute a remote command, multiple commands or a Bash script over SSH between remote Linux hosts and get back the output (result).

This information will be especially useful for ones, who want to create a Bash script that will be hosted locally on a one Linux machine but would be executed remotely on the other hosts over SSH.

Cool Tip: Connect to a remote SSH server without typing a password! Configure a passwordless authentication! Only 3 easy steps! Read more →

SSH: Execute Remote Command

Execute a remote command on a host over SSH:

Examples

Get the uptime of the remote server:

SSH: Run Multiple Remote Commands

Much more often it is required to send multiple commands on a remote server, for example, to collect some data for inventory and get back the result.

There are a lot of different ways of how it can be done, but i will show the most popular of them.

Run multiple command on a remote host over SSH:

$ ssh USER@HOST 'COMMAND1; COMMAND2; COMMAND3'

$ ssh USER@HOST 'COMMAND1 | COMMAND2 | COMMAND3'

Cool Tip: SSH login is too slow? This can be fixed easily! Get rid of delay during authentication! Read more →

Examples

Get the uptime and the disk usage:

$ ssh root@192.168.1.1 'uptime; df -h'

Get the memory usage and the load average:

$ ssh root@192.168.1.1 'free -m | cat /proc/loadavg'

Show the kernel version, number of CPUs and the total RAM:

SSH: Run Bash Script on Remote Server

The equally common situation, when there is some Bash script on a Linux machine and it needs to connect from it over SSH to another Linux machine and run this script there.

The idea is to connect to a remote Linux server over SSH, let the script do the required operations and return back to local, without need not to upload this script to a remote server.

Certainly this can be done and moreover quite easily.

Cool Tip: Want to ROCK? Start a GUI (graphical) application on a remote Linux workstation over SSH! Read more →

Example

Execute the local script.sh on the remote server:

23 Replies to “SSH: Execute Remote Command or Script – Linux”

Hi,
How about executing a command remotely and making sure that it will be killed once i kill my ssh session. or getting of PID of either SSH or the actual command on remote-node via a script.
Something like this I want to achieve:
Example: collecting pcap on remote addr and storing it locally.

$ ssh -t -f "tcpdump -w -" > /tmp/tcp.pcap

$ ssh ADDRESS 'echo "rootpass" | sudo -Sv && bash -s' < BASH_FILE

How do create a scrip to run commands on multiple remote machines?
When the first one gets executed, the response returned to STOUT, and the next one is not executed until I ^C the previous command.
I tried using ‘exit’ command and ‘&’ , neither is working.

Hello everyone,
I am new to linux and trying to learn it. I have task to complete “Get last 3 login details of list of linux machine with date and time.”
Is there any way to achive it? Thanks in advance

You should change these examples to use double quotes – I got tripped up putting variables in these single quotes and took me a while to realise bash treats it as a string…

como puedo hacer que solo me pida una vez la contraseña de mi servidor? hice mi escript y como realizo varias tareas me pide varias veces la contraseña

Can someone help me write a shell script to shutdown a Ubuntu computer?
I’m going to have it run on a Mac, so that it will ssh into the Ubuntu and shut it down. I need it to open Application “Terminal” then ssh name@123.45.67.89, then give it the password.
Then I need it to issue command “sudo poweroff”, and give it the password again.
I know how to do this manually by opening Mac’s Terminal. I just type in “ssh name@123.456.78.9, it asks for the password, I type it in, and it’s connected. Then I just type in “sudo poweroff” and it asks for the password again, I type it in, and bam, it shuts down the Ubunt computer.
The problem is, I need to automate this to do it at a specific time of day. On the Mac, there is what is called “Automator”, and you can set up ICalendar Events to run an “Automator Workflow” with a Shell Script. I just don’t know how to write the Shell Script to do what I can do manually? Any help is appreciated greatly!

I solved this. Here’s what works:
tell application “Terminal”
activate
do script (“ssh test@192.168.1.10“)
delay 6
do script “password” in front window
delay 7
do script “sudo poweroff” in front window
delay 5
do script “password” in front window
end tell

Why when I get a script from somewhere by curl & then pipe to bash to run it on my local server, some commands in a bash functions failed to execute, no error, no code error btw..just the called functions don’t execute.. How do I know my code is ok, because when I output it as a file from curl, I chmod and run it like ./..scriptfile.sh.. Code run fine.. Any idea and how do I resolve this?

This was very helpful for me. I am very new to this and just ordered a VPS yesterday and these guides are really helping me work my way around. I appreciate this simple resource you’ve put together!

how to run a script with sudo previllages on remote server: ssh -tt rundeck@$Batch_Host ‘ bash -s’ < /home/abhishekc/dem.sh i am getting permission denied

Источник

SSH Command - Usage, Options, Configuration

This page is about the OpenSSH ssh command on Unix/Linux or the Mac terminal. For general information about SSH and other implementations, see the SSH protocol home page .

Practically every Unix and Linux system includes the ssh command. This command is used to start the SSH client program that enables secure connection to the SSH server on a remote machine. The ssh command is used from logging into the remote machine, transferring files between the two machines, and for executing commands on the remote machine.

Contents

SSH Command in Linux

The ssh command provides a secure encrypted connection between two hosts over an insecure network. This connection can also be used for terminal access, file transfers, and for tunneling other applications. Graphical X11 applications can also be run securely over SSH from a remote location.

Other SSH Commands

There are other SSH commands besides the client ssh . Each has its own page.

• ssh-keygen - creates a key pair for public key authentication
• ssh-copy-id - configures a public key as authorized on a server
• ssh-agent - agent to hold private key for single sign-on
• ssh-add - tool to add a key to the agent
• scp - file transfer client with RCP-like command interface
• sftp - file transfer client with FTP-like command interface
• sshd - OpenSSH server

Using the Linux client

Linux typically uses the OpenSSH client. The ssh command to log into a remote machine is very simple. To log in to a remote computer called sample.ssh.com, type the following command at a shell prompt:

If this is the first time you use ssh to connect to this remote machine, you will see a message like:

The authenticity of host 'sample.ssh.com' cannot be established.

DSA key fingerprint is 04:48:30:31:b0:f3:5a:9b:01:9d:b3:a7:38:e2:b1:0c.

Are you sure you want to continue connecting (yes/no)?

Type yes to continue. This will add the server to your list of known hosts ( ~/.ssh/known_hosts ) as seen in the following message:

Warning: Permanently added 'sample.ssh.com' (DSA) to the list of known hosts.

Each server has a host key , and the above question related to verifying and saving the host key, so that next time you connect to the server, it can verify that it actually is the same server.

Once the server connection has been established, the user is authenticated. Typically, it asks for a password. For some servers, you may be required to type in a one-time password generated by a special hardware token.

Once authentication has been accepted, you will be at the shell prompt for the remote machine.

Specifying a different user name

It is also possible to use a different username at the remote machine by entering the command as:

ssh alternative-username@sample.ssh.com

The above can also be expressed with the syntax:

ssh -l alternative-username sample.ssh.com

Executing remote commands on the server

The ssh command is often also used to remotely execute commands on the remote machine without logging in to a shell prompt. The syntax for this is:

For example, to execute the command:

on host sample.ssh.com, type the following command at a shell prompt:

ssh sample.ssh.com ls /tmp/doc

After authenticating to the remote server, the contents of the remote directory will be displayed, and you will return to your local shell prompt. -x Disables X11 forwarding.

SSH client configuration file

The ssh command reads its configuration from the SSH client configuration file ~/.ssh/config . For more information, see the page on SSH client configuration file .

Configuring public key authentication

To configure passwordless public key authentication , you may want to create an SSH key and set up an authorized_keys file. See the pages on ssh-keygen and ssh-copy-id for more information.

Configuring port forwarding

Command-line options can be used to set up port forwarding. Local fowarding means that a local port (at the client computer) is tunneled to an IP address and port from the server. Remote forwarding means that a remote port (at the server computer) is forwarded to a given IP address and port from the client machine. See the page on configuring port forwarding on how to configure them.

OpenSSH also supports forwarding Unix domain sockets and IP packets from a tunnel device to establish a VPN (Virtual Private Network).

SSH command line options

Some of the most important command-line options for the OpenSSH client are:

-1 Use protocol version 1 only.

-2 Use protocol version 2 only.

-4 Use IPv4 addresses only.

-6 Use IPv6 addresses only.

-A Enable forwarding of the authentication agent connection.

-a Disable forwarding of the authentication agent connection.

-C Use data compression

-c cipher_spec Selects the cipher specification for encrypting the session.

-D [bind_address:] port Dynamic application-level port forwarding. This allocates a socket to listen to port on the local side. When a connection is made to this port, the connection is forwarded over the secure channel, and the application protocol is then used to determine where to connect to from the remote machine.

-E log_file Append debug logs to log_file instead of standard error.

-F configfile Specifies a per-user configuration file. The default for the per-user configuration file is ~/.ssh/config.

-g Allows remote hosts to connect to local forwarded ports.

-i identity_file A file from which the identity key (private key) for public key authentication is read.

-J [user@] host [:port] Connect to the target host by first making a ssh connection to the pjump host[(/iam/jump-host) and then establishing a TCP forwarding to the ultimate destination from there.

-l login_name Specifies the user to log in as on the remote machine.

-p port Port to connect to on the remote host.

-q Quiet mode.

-V Display the version number.

-v Verbose mode.

-X Enables X11 forwarding.

A little history

SSH replaced several older commands and protocols in Unix and Linux the 1990s. The include telnet , rlogin , and rsh .

SSH runs at TCP/IP port 22. This is right between ftp and telnet, which are 20 years older. Read the story of how SSH got port 22 .

The following video summarizes how and why SSH was originally developed.

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