cloud engineer
Generate a map of your live streaming viewers by placing of your viewer’s IP into a file and then using IPInfo’s map tool.
vim ipList
54.0.0.1
54.0.0.2
54.0.0.3 |
To plot the IPs on a map, pipe them to IPinfo.io.
cat ipList | curl -XPOST --data-binary @- "ipinfo.io/map?cli=1" |
The result is a URL of the map.
Install Speedtest CLI.
sudo apt-get install gnupg1 apt-transport-https dirmngr export INSTALL_KEY=379CE192D401AB61 sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys $INSTALL_KEY echo "deb https://ookla.bintray.com/debian generic main" | sudo tee /etc/apt/sources.list.d/speedtest.list sudo apt-get update sudo apt-get install speedtest |
To run.
speedtest |
Result.
$ speedtest
Speedtest by Ookla
Server: City of Columbus - Columbus, OH (id = 40410)
ISP: Spectrum
Latency: 9.39 ms (0.63 ms jitter)
Download: 117.74 Mbps (data used: 60.3 MB)
Upload: 11.81 Mbps (data used: 5.6 MB)
Packet Loss: 0.0%
Result URL: https://www.speedtest.net/result/c/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx (redacted) |
Install
yum install sos |
Run sosreport
sosreport |
Case number will be part of exported report located in /var/tmp.
cd /var/tmp |
If you want to SSH to a Docker container, use the Docker exec command.
docker exec -it container_name bash |
I’m using a Git Bash terminal, so I have to prefix the docker command with winpty.
winpty docker exec -it container_name bash |
Result
root@681bbe3f65f1:/var/www/html# |
Ctrl-D to exit.
Here’s how to troubleshoot nameservers with dig.
dig hostname dig domain.com |
To test a specific nameserver.
dig @nameserver hostname dig @nameserver ip-address |
Other options.
dig hostname.domain.com +short dig hostname.domain.com +noall +answer dig @nameserver MX domain.com dig @nameserver AAAA domain.com |
Here’s how to run a script on bootup on Rhel 7 that’s running systemd.
First create a script. It this case, it will create a file called test.txt.
#!/bin/bash > /root/test.txt |
Make the script executable.
chmod /root/test.sh |
Now create a service in /etc/systemd/system/test.service
# vi /etc/systemd/system/test.service [Unit] Description=A test service After=network.target [Service] Type=simple ExecStart=/root/test.sh TimeoutStartSec=0 [Install] WantedBy=default.target |
Reload systemd.
systemctl daemon-reload |
Enable the service.
systemctl enable test.service |
Start the service.
systemctl start test.service |
Reboot and test.
reboot |
Validate if the script ran. Check if the file was created.
It’s recommended to set the clock to UTC. In rare occasions, local time may be needed.
Here’s how to set your server’s timezone permanently.
Check the date first.
date |
Backup localtime. Set it to US Eastern Time.
mv /etc/localtime /etc/localtime.backup ln -s /usr/share/zoneinfo/America/New_York /etc/localtime |
Backup clock. Set it to US Eastern Time.
cp -p /etc/sysconfig/clock /etc/sysconfig/clock.backup > /etc/sysconfig/clock echo ZONE=\"America/New_York\" > /etc/sysconfig/clock |
Run the date again to validate.
date |
Here’s a simple little script that displays the number of characters in a string.
#!/bin/bash if [[ $# -eq 0 ]] ; then echo 'Missing arguments'; exit 0; fi var=$1 size=${#var} echo $size |
Command:
./length.sh abcdefghijklmnopqrstuvwxyz |
Output:
26 |
I decided to log my commands for good record keeping. Here’s my script.
#!/bin/bash if [[ $# -eq 0 ]] ; then echo 'No arguments. Format: ./go.sh script.sh'; exit 0; fi log=log.txt echo '-------------------------------' >> $log date >> $log echo '---' >> $log cat $1 >> $log echo '---' >> $log /bin/bash $1 2>&1 | tee -a $log |
To run.
./go.sh script.sh |
Line by line explanation.
How to create a swap file.
A 2GB swap file.
dd if=/dev/zero of=/swapfile bs=1k count=2048k |
Activate.
mkswap /swapfile chmod 0600 /swapfile systemctl daemon-reload swapon /swapfile |
To make swap permanent, add to /etc/fstab.
/swapfile swap swap defaults 0 0 |
Check if swap is working.
cat /proc/swaps free -h |