Uly.me

cloud engineer

check

Check If Domain Joined

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Here’s the command to check if instance is domain joined.

realm discover domain.com

To check if AD user is working.

id user@ad.example.com

To check if AD group is working.

getent group ad-group

GCE Agent Powershell

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This is a Powershell script to restart a service if it’s down.

$ServiceName = 'GCEAgent'
$arrService = Get-Service -Name $ServiceName
 
if ($arrService.Status -ne 'Running')
{
 
    Start-Service $ServiceName
    write-host $arrService.status
    write-host 'Service starting'
    Start-Sleep -seconds 60
    $arrService.Refresh()
    if ($arrService.Status -eq 'Running')
    {
        Write-Host 'GCE Agent Service is now Running'
    }
 
}
else
{
    Write-Host 'GCE Agent Service is Running'
}

GCP Check Instances Running

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Here’s how to check if instances are running in GCP. 

#!/bin/bash
while IFS=', ' read -r a b c; do
  instance="${a//[[:blank:]]/}"
  project="${b//[[:blank:]]/}"
  zone="${c//[[:blank:]]/}"
  gcloud compute instances describe $instance \
  --zone $zone --project $project \
  --format='table[no-heading](name,status,zone)'
done < instance-list.txt

Instances are read from an external file. File is comma delimited with instance name, project id and zone data.

Removing Old Kernels

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How to check which kernel is running on your system

uname -sr

List all kernels installed on the system.

rpm -q kernel

Removing old kernels using package-cleanup. This keeps 2 kernels on the system.

yum install yum-utils
package-cleanup --oldkernels --count=2

RPM Check Packages

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How to check RPM if packages are installed.

rpm -qa --last 
rpm -qa --last | more
rpm -qa --last | grep "package name"

Check Memory in Linux

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Here are several commands to check memory in Linux.

free -m
cat /proc/meminfo
vmstat -s
top

Check Argument in Bash

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How to check for an argument in a script in Bash.

if [ -z "$1" ] ; then
  echo "there are no arguments"
else
  echo "there is an argument"
fi