Script to take a list of hostnames to ssh into and run commands?

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Windows 10 script (either PS or cmd) script to ssh into a list of hostnames (running centos) and run a few commands, then logout. Run through each hostname in list until it is done?

Is this possible?

2

Could do this in bash, if you've got Linux subsystem installed.

for host in $(cat $1)
do
    ssh $host echo "echo on remote host"
done

Script syntax looks like:

remoterun ~/hosts.txt

I don't really have knowledge of PS/cmd, but I'm not sure that it's easy to do because of the way PS and cmd are built. They feel really clunky to me.

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3

PowerShell was made to be as friendly to Linux and Bash users as possible. Many common Bash commands are aliased to the equivalent PowerShell commands. ls will list files in a directory for example. It's actual command is Get-Child (I hate this naming convention with a passion, but everything in PowerShell is done that way).

Here's an example of a script I use to convert files in Handbrake to another format:

$search = GCI $PSScriptRoot -Include *.mkv, *.mp4 -recurse -Exclude *_HEVC*;
$output = '';

If (!(Test-Path -Path ..\Uploading))
{
    New-Item -ItemType directory -Path ..\Uploading;
}

foreach ($file in $search)
{
	$newfilename = $file.BaseName + "_HEVC" + $file.Extension -replace ".mp4",".mkv";
	$newfile = $file.DirectoryName + "\" + $newfilename; 

	HandBrakeCLI.exe -P -e x265 --encoder-preset slow -x strong-intra-smoothing=0:rect=0 -q 16.0 --vfr --all-audio -E copy -B 160 --all-subtitles -i $file -o $newfile -f av_mkv;
}

So if you used that as a template, since all it does is get a list of paths using Get-Child, then runs a command using the information from that list of paths, you could easily do what you wanted.

First you need a list of host names or their IP addresses. If you can generate that into a text file, then you can just use that in place of a file listing.

An example:

$hosts = [System.IO.File]::OpenText("hosts.txt"); #hosts.txt is your text file; 
# needs to be in same location as where you are running this command from.
$output = ''; #Just stating the variable for logging purposes.

try{
    for() #Overall, this for repeats through the txt file running SSH commands on
    { #each host.
        $host = $hosts.ReadLine() #Uses ReadLine function to read 1 line
        if ($host -eq $null) { break } #If the line is equal to null, it breaks
        ssh $host <do other stuff> #Your SSH command to login
        <do more stuff> #Commands to run once SSH'd in
        <exit ssh session> #Exits the session.
    }
finally {
    $reader.Close() #Closes the reader safely. Something something open files and
} #data loss.

That's just a powershell script. @KenPC

A shorter way to do it:

$reader = [System.IO.File]::OpenText("hosts.txt") #Opens file for reading
while($null -ne ($host = $reader.ReadLine())) { #While line does not equal NULL
    ssh $host #ssh into host
    <do stuff> #do commands
    <exit ssh session> #exit ssh session
} #will repeat until NULL line is hit (end of file)

Just copy/paste that into a text file with the extension .ps1 and it should run using PowerShell.

If you want to run tests while editing it, definitely use PowerShell's ISE. https://msdn.microsoft.com/en-us/powershell/scripting/core-powershell/ise/introducing-the-windows-powershell-ise

It's built into Windows 10. Should come up alongside PowerShell if you search PowerShell.

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4

thanks! but i'm going to have to log into the machines using my account and elevate to su before doing the command I need to run on each box.

I have a sudo command I need to run on 50+ centos machines :frowning:

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5

At this point, you should really be using Ansible.

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6

thanks, i'll have to look into that

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7

Another vote for Ansible. Article on running it with windows subsystem for linux: https://www.jeffgeerling.com/blog/2017/using-ansible-through-windows-10s-subsystem-linux

Another alternative is running a linux vm for Ansible. Seems heavy, but worth it in the long run.

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8

Yeah, with that many machines, the only way to efficiently manage them is via something along the lines of this. Ansible is agentless, but chef has better file-consistency management.

All in all, I'd go with Ansible and just stick through the learning curve.

9

I actually have all of them connected to a spacewalk server i built, but in order to enable the remote command feature, all of the clients had to have that feature enabled. which required a command ran as su.

I ended up logging into all of them and doing it manually. Carpal tunnel should be coming soon. lol. I was just looking for a quick dirty way to do it quicker.

I can run bulk remote commands now all at once. Thanks anyways huys. I'll still be looking at ansible

10

Oh, lol that would explain a lot.

I would just go ahead and start manually SSHing or set up key exchange with your local user and run a script.