CATEGORY: Linux

How to Prevent Raspberry Pi Zero from Blanking or Sleeping

I was setting up a Raspberry Pi Zero in an office to use for displaying a slide show of pictures on a TV in the waiting room and dismayed to learn it would constantly go to sleep after a few minutes. I researched and tried setting the consoleblank=0 in config.txt with no luck along many other solutions, but learned none of them worked for the Raspberry Pi Zero.

I finally figured out one fix that worked that’s easy to use. Open Terminal and run the following command:

I’m not sure why, but I got an error that some dependencies were not installed. If that happens to you as well, run this command in terminal:

and then run the install for xscreensaver again

Now under Preferences, you’ll see a new option for screen saver.

On the Display Modes tab, you’ll see a drop down for Mode. Choose “Disable Screen Saver”

Your raspberry pi zero will now no longer go to sleep.

How to test email sending in Laravel 5.3 using artisan tinker

I’m building a Laravel app and ran into an error when trying to send mail but wasn’t getting an error back since the request was posted through ajax. If you’re trying to troubleshoot it, artisan tinker app is very useful to get more information on the error.

Fire up terminal/command line and run:

and then run the following snippet:

Change emails.test to point to a blade that works and populate the email you want to test.

You should either see a success/null message if everything was correct, or an error with details on what went wrong. The error I encountered required configuring 2FA in Gmail or setting the insecure app option up to send through Gmail for testing.

How to repair permissions on Linux Apache /var/www/html folder

I recently ran into an issue where I could no longer FTP files to my Linux droplet when multiple users were uploading to the server. The server kept the user as the owner despite me adding them to the www-data group. This fix comes from my ex-boss, James Tomasino who was kind enough to provide some help since I was stumped. I’m sharing in case anyone else runs into the same issue and finds it useful.

You’ll need to fire up terminal, ssh to the server, and then execute these commands:

+s makes permissions sticky so that all files will inherit from the parent directory. This was the setting I was missing.

Open up /etc/ssh/sshd_config. I use nano so:

Hit CTRL+W and look for “subsystem” which is typically located near the bottom of the file. Change

to

If you already have files in the HTML folder, you’ll want to run these commands to reset the permissions:

 

How to stop CouchDB on Mac OS

I have been working on a proof of concept using CouchDB. After getting the proof of concept working, I spun up a digital ocean droplet and proceeded to setup CouchDB on the server. I went to enable the SSH tunnel so I could access the CouchDB Futon instance and promptly ran into an error because my local instance of CouchDB was using the same port, 5984. I had a lot of trouble finding out an easy way to stop CouchDB because the documentation in the Wiki wasn’t accurate:

As a workaround, in Terminal, run

This will output something like:

99093 0 org.apache.couchdb.288008

Grab the highlighted portion and run

Substitute the process name accordingly and you should be able to run the ‘launchctl list’ command again and see the process is no longer present.

(98)Address already in use: AH00072: make_sock: could not bind to address [::]:80 – error

I recently got handed a new Ubuntu droplet at work to setup and work on. I was going through the typical configuration to lock down the server and go to installing Apache when I suddenly ran into the error

(98)Address already in use: AH00072: make_sock: could not bind to address [::]:80 – error

I was a little surprised considering I had only run 4 commands total on a brand new installation. If you’re getting this error like me, you’ll need to find out what’s being bound to port 80 and then stop it. Use this command to get a list of anything that’s running on port 80.

For me, it turned out nginx was running and bound to port 80. If you have the same problem, run this command to stop it:

Now you should be able to start apache.

Copy File Context to Clipboard via Command Line, Git Bash (Mingw64), or Terminal

I’ve been spending more time switching from SVN to Git and learning the command line options. I’m finding a lot of the Mac Git terminal commands I run aren’t the same in Git Bash (Mingw64). One of the commands I use is the pbcopy command to copy the ssh key to the clipboard to paste into Github and Bitbucket accounts. I’m starting to use it more as I am learning managing Linux servers and adding my key to login. I’m adding it here as a cheatsheet for myself but I thought others may find it useful.

On Windows, you can run this command to copy your ssh key to the clipboard:

On Mac:

or if you want to view it in the terminal window:

How to Copy and Paste into the Digital Ocean VNC Console

I recently signed up for Digital Ocean to test droplets for my development and linux management testing. I was securing the server and setup fail2ban, disabled the root login, and created a user account but forgot to change the user name from root to the user name I selected in my SSH client profile. I ended up locking myself out of the server and had to resort to logging into the admin panel on Digital Ocean’s website and use their browser embedded VNC client to restore my access. I quickly discovered that one of the downsides of using this panel is that you can’t copy and paste commands. Luckily there’s a workaround and you can use the browser console to do sendkeys through Javascript.

Bring up the console in the browser developer tools. Here’s a cheat sheet for keyboard shortcuts:

BrowserDescriptionWindowsMac
ChromeOpen Developer Tools and bring focus to the consoleCtrl + Shift + JCmd + Opt + J
FirefoxOpen ConsoleCtrl + Shift + KCmd + Opt + K
Internet ExplorerAfter hitting F12, you have to click the console tab.
There’s no direct shortcut to the console tab.
F12N/A

Paste this snippet into the textbox in the console window:

Chrome console

 

Update 9-21-16

Ruden and Sebastiaan’s pointed out there was a bug in the code above. This updated snippet has support for characters when using shift characters like !@#$%^&*()_+

You’ll receive a dialog prompt to enter the copy to paste in. Please note that you need to click on the VNC console and hit enter to execute the command.

Javascript Prompt

 

 

 

 

 

If you need to enter more than one command, just hit the up arrow on your keyboard in the console to get the script again for easy reuse.

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