Raspberry, Ubuntu and Megatools

Posted on 17 June 2020 by kosmas

To install megtools (command line utilities for Mega.nz), in your raspberry with ubuntu installed follow the steps below (thanks to the instructions from here: https://www.instructables.com/id/Descarga-archivos-de-Mega-con-Raspberry-Pi/)

Install the necessary packages

sudo apt-get -y install build-essential libglib2.0-dev libssl-dev libcurl4-openssl-dev libgirepository1.0-dev 

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						sudo apt-get -y install build-essential libglib2.0-dev libssl-dev libcurl4-openssl-dev libgirepository1.0-dev

You may also need to add some additional packages if there is an error about the documentation.

Get the latest source code from https://megatools.megous.com

wget https://megatools.megous.com/builds/megatools-1.10.3.tar.gz

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						wget https://megatools.megous.com/builds/megatools-1.10.3.tar.gz

Compile and install them

tar xvfz megatools-1.10.3.tar.gz
cd megatools-1.10.3
./configure
make
sudo make install
sudo ldconfig

				
					
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						tar xvfz megatools-1.10.3.tar.gz
cd megatools-1.10.3
./configure
make
sudo make install
sudo ldconfig

					

			

Add your Mega account credentials in ~/.megarc like:

[Login]
Username = my_mega@email
Password = mypassword

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						[Login]
Username = my_mega@email
Password = mypassword

use the mega tools commands (megacopy, megals, megaget etc.

WiFi, Raspberry Pi 4 B, Ubuntu 20.04

Posted on 10 June 2020 by kosmas

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After installing an image of the Ubuntu server on the Raspberry 4, the wifi is not automatically configured after the initial book.

In order to be able to use the WiFi follow the steps described below for setting up your wifi in your SD card, and then reboot your raspberry (make sure that the indentation in the yaml file is correct, and also your WiFi access point is enclosed in quotes):

https://ubuntu.com/tutorials/how-to-install-ubuntu-on-your-raspberry-pi#3-wifi-or-ethernet

restarting X Window Server from command line in linux

Posted on 2 June 2020 by kosmas

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To restart your X Window Server from the command line in linux, without affecting any non-graphical programs (but losing any unsaved information in your graphical user interface programs), you can use the following:

sudo systemctl restart display-manager

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						sudo systemctl restart display-manager

Find devices with their IPs in your local network

Posted on 10 March 2020 by kosmas

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Problem

You would like to have a list of IPs or MAC address for the device in your network

Solution

Use the ARP protocol’s command:

$ arp -a

dv1.home (192.168.1.102) at 48:xx:xx:xx:xx:xx [ether] on wlp4s0
dv2.home (192.168.1.127) at a4:xx:xx:xx:xx:xx [ether] on wlp4s0
...

Find your public IP address from linux command line

Posted on 13 January 2020 by kosmas

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Problem

You would like to find out your public IP from the command line without using an online service

Solution

Use dig like the following line (taken from https://www.cyberciti.biz/faq/how-to-find-my-public-ip-address-from-command-line-on-a-linux/):

dig +short myip.opendns.com @resolver1.opendns.com

you could also add it as an alias:

alias myip=”dig +short myip.opendns.com @resolver1.opendns.com”

Get a list for all crontab jobs in a server

Posted on 6 December 2019 by kosmas

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To get a list of all the installed crontab jobs on a server use the following (taken from https://stackoverflow.com/a/134944)

for user in $(cut -f1 -d: /etc/passwd); do echo $user; crontab -u $user -l; done

Automatic emails using bash and sendgrid

Posted on 24 November 2018 by kosmas

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Problem

You would like to be able to automatically send some emails (ie reports) from a linux server, using a bash script that runs in cronjob, without installing an email server on the linux server.

Solution

Create an account in Sendgrid and follow the directions for using WebAPI with curl
here

Set up your bash script to use the API key and have a script like the following. If you want to use big or multiple files you will need to use a temporary file for the base64 encoding, as in the example below, as there is a limit in curl.

#!/bin/bash

# Email setup
SENDGRID_API_KEY="your_sendgrid_api_key"
FILENAME_ATTACH="title_of_your_attachment"
FILENAME_ZIP="the_path_to_your_zip_file"
FILENAME_BASE64_TMP="the_path_to_temporary_base64_encoding"
EMAIL_TO="email_to_address"
EMAIL_SUBJECT="email_subject"
EMAIL_FROM="email_from_address"
EMAIL_MESSAGE="your_email_message"

function email_exports()
{
  FILENAME_BASE64=$(base64 -w0 $FILENAME_ZIP);

  REQUEST_DATA='{"personalizations": [{
                        "to": [{ "email": "'"$EMAIL_TO"'" }],
                        "subject": "'"$EMAIL_SUBJECT"'"
                }],
                "from": {
                        "email": "'"$EMAIL_FROM"'"
                        },
                "content": [{
                        "type": "text/plain",
                        "value": "'"$EMAIL_MESSAGE"'"
                        }],
                "attachments": [{
                        "content": "'"$FILENAME_BASE64"'",
                        "filename": "'"$FILENAME_ATTACH"'"
                        }]
  }';

  # We need to store the base64 locally as the text
  # is too big for sending directly with curl
   echo $REQUEST_DATA > $FILENAME_BASE64_TMP

   curl -X "POST" "https://api.sendgrid.com/v3/mail/send" \
        -H "Authorization: Bearer $SENDGRID_API_KEY" \
        -H "Content-Type: application/json" \
        -d "@$FILENAME_BASE64_TMP";

   rm $FILENAME_BASE64_TMP
}

email_exports

#!/bin/bash

# Email setup

SENDGRID_API_KEY="your_sendgrid_api_key"

FILENAME_ATTACH="title_of_your_attachment"

FILENAME_ZIP="the_path_to_your_zip_file"

FILENAME_BASE64_TMP="the_path_to_temporary_base64_encoding"

EMAIL_TO="email_to_address"

EMAIL_SUBJECT="email_subject"

EMAIL_FROM="email_from_address"

EMAIL_MESSAGE="your_email_message"

function email_exports()

{

FILENAME_BASE64=$(base64 -w0 $FILENAME_ZIP);

REQUEST_DATA='{"personalizations": [{

"to": [{ "email": "'"$EMAIL_TO"'" }],

"subject": "'"$EMAIL_SUBJECT"'"

}],

"from": {

"email": "'"$EMAIL_FROM"'"

"content": [{

"type": "text/plain",

"value": "'"$EMAIL_MESSAGE"'"

}],

"attachments": [{

"content": "'"$FILENAME_BASE64"'",

"filename": "'"$FILENAME_ATTACH"'"

}]

}';

# We need to store the base64 locally as the text

# is too big for sending directly with curl

echo $REQUEST_DATA > $FILENAME_BASE64_TMP

curl -X "POST" "https://api.sendgrid.com/v3/mail/send" \

-H "Authorization: Bearer $SENDGRID_API_KEY" \

-H "Content-Type: application/json" \

-d "@$FILENAME_BASE64_TMP";

rm $FILENAME_BASE64_TMP

}

email_exports

Add your script to crontab

ERROR: Couldn’t connect to Docker daemon at http+docker://localunixsocket – is it running?

Posted on 17 October 2018 by kosmas

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Problem

Using docker-compose up (or build), displays the following error message (even though the same command used to work previously):

ERROR: Couldn't connect to Docker daemon at http+docker://localunixsocket - is it running?

1	ERROR: Couldn't connect to Docker daemon at http+docker://localunixsocket - is it running?

Solution

This is quite possible caused by permissions issue, as one of the folders files that docker is trying to use is owned by a different user/group from the one trying to use the docker-compose commands. Try to find the file/folder with the different permissions and change it to your user name and group, or use change the files by using something like:

chown -R me:me .

1	chown -R me:me .

Copying files between two folders without overwriting existing ones in destination folder.

Posted on 21 June 2018 by kosmas

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Problem

You would like to copy the contents of a source directory to a destination directory without overwriting existing files on the destination.

Solution

You can use

rsync -a -v --ignore-existing source_dir/ dest_dir/

1	rsync -a -v --ignore-existing source_dir/ dest_dir/

and you can also use the –dry-run option to test before running it.

Bash getting the parent folder name from a bash defined variable

Posted on 14 November 2017 by kosmas

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Problem

You have defined a variable in a bash script (ie MY_FOLDER) but you also want to dynamically get the parent folder (ie MY_FOLDER can have multiple values).

Solution

Use the dirname as in the following

MY_FOLDER=/home/user/first_folder/second_folder
MY_PARENT_FOLDER=$(dirname $MY_FOLDER)

echo $MY_FOLDER
echo $MY_PARENT_FOLDER

.......
/home/user/first_folder/second_folder
/home/user/first_folder

MY_FOLDER=/home/user/first_folder/second_folder

MY_PARENT_FOLDER=$(dirname $MY_FOLDER)

echo $MY_FOLDER

echo $MY_PARENT_FOLDER

.......

/home/user/first_folder/second_folder

/home/user/first_folder

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Web notebook about thoughts and discoveries in DevOps, SRE, Software Engineering….

Category Archives: Bash

Raspberry, Ubuntu and Megatools

WiFi, Raspberry Pi 4 B, Ubuntu 20.04

restarting X Window Server from command line in linux

Find devices with their IPs in your local network

Problem

Solution

Find your public IP address from linux command line

Problem

Solution

Get a list for all crontab jobs in a server

Automatic emails using bash and sendgrid

ERROR: Couldn’t connect to Docker daemon at http+docker://localunixsocket – is it running?

Copying files between two folders without overwriting existing ones in destination folder.

Bash getting the parent folder name from a bash defined variable