Tag Archives: startup

CLI, Hardware, Networking

piKVM pushover startup script

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I’ve had an issue where I wasn’t sure if my dynamic DNS provider registered properly. I then realized that I have a piKVM attached to one of my servers that boots on powerup, even if the server does not. I could utilize this piKVM to help me out.

Thanks to inspiration from Chris Dzombak I was able to whip up a little script that runs on startup. This script waits 5 minutes to allow for my firewall and modem to boot up, then sends a pushover notification to let me know the piKVM is online and what its external IP address is.

To get it working on the piKVM I had to enter into RW mode, write and save the script, add execute permissions to the script, then configure a systemd service to run the script at startup.

Here is the script, saved under /root/boot-pushover.sh

#!/usr/bin/env bash
set -eu

#Wait 5 minutes to allow router bootup
sleep 300

TOKEN="PUSHOVER_APPLICATION_TOKEN"
USER="PUSHOVER_USER_TOKEN"
EXTERNAL_IP="$(curl ifconfig.me)"
MESSAGE="$(hostname) is online. External IP: $EXTERNAL_IP"

#Send pushover command to alert it's up and send its external IP
curl -s \
  --form-string "token=$TOKEN" \
  --form-string "user=$USER" \
  --form-string "message=$MESSAGE" \
  https://api.pushover.net/1/messages.json

Set executable: chmod +x /root/boot-pushover.sh

Here is the systemd service, saved under /etc/systemd/system/boot-pushover-notification.service

[Service]
Type=oneshot
ExecStart=/root/boot-pushover.sh
RemainAfterExit=yes
User=root
Group=root
RestartSec=15
Restart=on-failure

[Unit]
Wants=network.target
After=network.target nss-lookup.target

[Install]
WantedBy=multi-user.target

Reload daemons & enable startup: 

systemctl daemon-reload
systemctl enable boot-pushover-notification.service

Test by exiting rw mode and rebooting the piKVM:

ro
reboot

It works really well!

CLI, OS

Mount encfs folder on startup with systemd

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A quick note on how to encrypt a folder with encfs and then mount it on boot via a systemd startup script. In my case the folder is located on a network drive and I wanted it to happen whether I was logged in or not.

Create encfs folder:

encfs <path to encrypted folder> <path to mount decrypted folder>

Follow the prompts to create the folder and set a password.

Next create a file which will contain your decryption password

echo "YOUR_PASSWORD" > /home/user/super_secret_password_location
chmod 700 /home/user/super_secret_password_location

Create a simple script to be called by systemd on startup using cat to pass your password over to encfs

#!/bin/bash
cat super_secret_password_location | encfs -S path_to_encrypted_folder path_to_mount_decrypted_folder

Finally create a systemd unit to run your script on startup:

vim /etc/systemd/system/mount-encrypted.service
[Unit] 
Description=Mount encrypted folder 
After=network.target 

[Service] 
User=<YOUR USER> 
Type=oneshot 
ExecStartPre=/bin/sleep 20 
ExecStart=PATH_TO_SCRIPT
TimeoutStopSec=30 
KillMode=process 

[Install] 
WantedBy=multi-user.target

Then enable the unit:

sudo systemctl daemon-reload
sudo systemctl enable mount-encrypted.service
CLI, OS

Simple network folder mount script for Linux

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I wrote a simple little network mount script for Linux desktops. I wanted to replicate my Windows box as best as I could where a bunch of network drives are mapped upon user login. This script relies on having gvfs-mount and the cifs utilities installed (installed by default in Ubuntu.)

#!/bin/bash
#Simple script to mount network drives

#Specify network paths here, one per line
#use forward slash instead of backslash
FOLDER=(
  server1/folder1
  server1/folder2
  server2/folder2/folder3
  server3/
)

#Create a symlink to gvfs mounts in home directory
ln -s $XDG_RUNTIME_DIR/gvfs ~/Drive_Mounts

for mountpoint in "${FOLDER[@]}"
do
  gvfs-mount smb://$mountpoint
done

Mark this script as executable and place it in /usr/local/bin. Then make it a default startup application for all users:

vim /etc/xdg/autostart/drive-mount.desktop
[Desktop Entry]
Name=Mount Network Drives
Type=Application
Exec=/usr/local/bin/drive-mount.sh
Terminal=false

Voila, now you’ve got your samba mount script starting up for every user.

CLI

Using screen to run interactive programs at startup

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Oftentimes I will encounter programs that weren’t necessarily designed to be automatically run that I want to run on startup. Sometimes that program will have interactive information that you will want to see later, but you still want it to run on startup.

The solution to this particular problem is using screen in combination with su and bash. In my situation, I want to run the HDSurfer plugin on bootup as a different user. The solution I came up is as follows (thanks to superuser.com and stackoverflow.com for the guidance I needed to set this up.)

Install screen

Screen is like having a separate X window session to keep a program running, except it is for console programs. You can attach and detach to this screen whenever you’d like and not worry about the program terminating.

sudo apt-get install screen

Create a script to run your program with all required arguments

In my case I needed to execute the command “python /usr/bin/HDSurferWave/hdsurferwave.py start” as a different user in a screen session (so it wouldn’t terminate when the terminal session did.) To do this,

  • invoke screen with the -dm command (to begin the program in detached mode)
  • issue the bash -c argument afterward to invoke bash
  • Include your desired command after that

My one line script looks like this:

screen -dm bash -c "python /usr/bin/HDSurferWave/hdsurferwave.py start"

Run your script

I use the su command with the -c argument to change the user that will be running the script, as the startup script launches things as root by default (with pre-systemd systems, anyway.) The -s command initiates a shell to launch, and the last argument is the user you want to run as. My launch argument is:

su -c "/usr/bin/HDSurferWave/start.sh" -s /bin/sh nicholas

Configure the script to run on startup

Edit /etc/rc.local and add your script command from above, then mark that file as executable by running chmod +x /etc/rc.local. Note: This will not work with systems using systemd.