Execute commands simultaneously on multiple servers Using PSSH/Cluster SSH/Multixterm
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In this tutorial we will see some tools to execute one command on multiple remote servers using ssh.First you need to make sure you have ssh installed in your machine or you can install using the following command
sudo aptitude install ssh
Now we are going to see the following tools which does the required job we are looking for
1) Pssh
2) cluster ssh
3) Multixterm
1) Pssh
pssh provides a number of commands for executing against a group of computers, using SSH. It's most useful for operating on clusters of homogenously-configured hosts.
The package contains:
-- Parallel ssh (parallel-ssh, upstream calls it pssh), executes commands on multiple hosts in parallel
-- Parallel scp (parallel-scp, upstream calls it pscp), copies files to multiple remote hosts in parallel
-- Parallel rsync (parallel-rsync, upstream calls it prsync), efficiently copies files to multiple hosts in parallel
-- Parallel nuke (parallel-nuke, upstream calls it pnuke), kills processes on multiple remote hosts in parallel
-- Parallel slurp (parallel-slurp, upstream calls it pslurp), copies files from multiple remote hosts to a central host in parallel
These tools are good for controlling large collections of nodes, where faster alternatives
Install pssh in Ubuntu
sudo aptitude install pssh
pssh Syntax
pssh command -h hosts-file options
-h --hosts hosts file (each line "host[:port] [user]")
-l --user username (OPTIONAL)
-p --par max number of parallel threads (OPTIONAL)
-o --outdir output directory for stdout files (OPTIONAL)
-t --timeout timeout in seconds to do ssh to a host (OPTIONAL)
-v --verbose turn on warning and diagnostic messages (OPTIONAL)
-O --options SSH options (OPTIONAL)
where the hosts-file contains a list of all the hosts that you want to have the command executed on.
pssh Examples
The following example runs hostname on three machines (IPs or hostnames) specified in the file ips.txt using login irb2 and saves the output in /tmp/foo.
sudo cat ips.txt
128.112.152.122
18.31.0.190
128.232.103.201
sudo pssh -h ips.txt -l irb2 -o /tmp/foo hostname
Success on 128.112.152.122:22
Success on 18.31.0.190:22
Success on 128.232.103.201:22
sudo ls /tmp/foo
128.112.152.122 128.232.103.201 18.31.0.190
sudo cat /tmp/foo/*
planetlab-1.cs.princeton.edu
planetlab1.xeno.cl.cam.ac.uk
planetlab1.lcs.mit.edu
By default, pssh uses at most 32 ssh processes in parallel to ssh to the various nodes. (This is somewhat important if you're controlling hundreds or thousands of machines.) By default, it also uses a timeout of one minute to ssh to a node and obtain a result. For ssh commands that take longer than this (e.g., sleep 61), the -t option can be used. Note that pssh and pnuke have a default timeout of one minute. pscp and prsync have no default timeout, but one can be specified using the -t option.
pscp
Here's an example of using pscp to copy files in parallel to a set of machines.
sudo pscp -h ips.txt -l irb2 /etc/hosts /tmp/hosts
Success on 128.112.152.122:22
Success on 18.31.0.190:22
Success on 128.232.103.201:22
Using the -r option will perform a recursive copy for copying entire directories.
2) cluster ssh
administer multiple ssh or rsh shells simultaneouslyClusterSSH allows you to control multiple ssh or rsh sessions from a single input window. You can also configure clusters of machines for easy invocation and interact with individual terminal windows during a session.
Install Cluster ssh in Ubuntu
sudo aptitude install clusterssh
Configuration Files
This /etc/clusters file is cluster tag database. Contains a list of tags and hostnames, in the form
<tag> [<username>@]hostname [...]
Newlines and comments (delimited with a #) are ignored.
Cluster definitions can also be added to the $HOME/.csshrc file
This /etc/csshrc file is Global configuration file, sourced by all users. Can be generated by:
sudo cssh -u > /etc/csshrc
$HOME/.csshrc
Per user configuration file. Can be generated by:
cssh -u > /etc/csshrc </tt>
To add a cluster definition to this file, use the following format
cluster_tag1 = server1 server2 [email protected]
cluster_tag2 = server4 server5
clusters = cluster_tag1 cluster_tag2
Be aware of using “reserved names” and no check is currently performed for them.
Using Cluster SSH
If you want to perform the same command on the three servers one, two, & three use the following command
sudo cssh one two three
This will open three consoles, one for each server, over an ssh connection, and one little console to type your command.
3) Multixterm
Expect is a program that talks to other interactive programs according to a script. Expect is useful for running any program which requires interaction between the program and the user.In Ubuntu multixterm included in expect package.
Install expect in Ubuntu
sudo aptitude install expect
Multixterm Syntax
multixterm -[ args ] "command arg1 arg2" server1 server2...
Arguments
-xa -- The optional -xa argument indicates arguments to pass to xterm.
-xc -- The optional -xc argument indicates a command to be run in each named xterm (see -xn). With no -xc argument, the command is the current shell.
-xd -- The optional -xd argument indicates a directory to search for files that will appear in the Files menu. By default, the directory is: ~/lib/multixterm
-xf -- The optional -xf argument indicates a file to be read at startup. See FILES below for more info.
-xn -- The optional -xn argument indicates a name for each xterm. This name will also be substituted for any %n in the command argument (see -xc).
-xv -- The optional -xv flag puts multixterm into a verbose mode where it will describe some of the things it is doing internally. The verbose output is not intended to be understandable to anyone but the author.
Multixterm Examples
The following command line starts up two xterms using ssh to the hosts 192.168.2.100 and 192.168.2.101
sudo multixterm -xc "ssh root@%n" 192.168.2.100 192.168.2.101
-xc -- The optional -xc argument indicates a command to be run in each named xterm (see -xn). With no -xc argument, the command is the current shell.
ssh root@%n : ssh is a command to connect remote server with root user. This name will also be substituted for any %n in the command argument.
Nice post (as allways) you forget “dsh” the famous dancer’s shell, or distributed shell I used it on openmosix cluster very usefull 😉
keep going
max
On Hardy Heron (8.04) you need to run parallel-ssh instead of pssh.
There is also the excellent ‘clusterit’.
Happy clustering
krishan
Wow this is crazy. I’m a user of iTerm on Mac OS X and there’s an option to send keyboard input to all tabs. So I load 5 or 6 tabs and ssh in each tab to my target machine. I then send input to all tabs and whatever I type on one tab, goes to the others. I can use command+right to switch tabs quickly so I can make sure every machine is ‘on the same page’. This allows for interactive programs like vi and top and allows you to edit files on all the tabbed servers simultaneously. I’m looking for something similar in Linux. clusterit, dsh, multixterm, cssh, pssh all seem geared toward doing it all from the GUI and being blind to whats going on in the remote machines. What if one doesn’t respond quite like the others or gets stuck somewhere? I need a GUI solution like iTerm for Linux workstations unfortunately.
I use iTerm on Mac also.
Try Terminator for Linux:
http://www.tenshu.net/p/terminator.html
Great post. Appreciate if you can modify the commands, as pssh has been renamed to parallel-ssh and pscp has been renamed to parallel-scp.
The rename has been done on ubuntu to avoid confusion with putty packages.
Good post, how can i use pssh on multiple servers that have different passwords?