Refresher on bash with Orange Pi specifics

While working with a Linux based SBC it is good to know your way around the bash shell.

The command prompt can be customized to show different information or symbols, depending on the user's preferences and the shell configuration. To enter a command, the user can type it after the prompt symbol and press Enter. The shell will then execute the command and display the output or any errors.

bash

pi@orangepi ~$

This is a command prompt in a bash shell, which is a common way to interact with a Linux operating system. It shows the following information:

pi is the username of the current user who is logged in.
@ is a separator that indicates the next part is the hostname of the computer.
orangepi is the hostname of the computer, which is a unique name that identifies it on a network.
~ is a shorthand for the home directory of the current user, which is where their personal files and settings are stored. It is equivalent to /home/pi in this case.
$ is a prompt symbol that indicates the shell is ready to accept commands from the user.

You can always check the above with the commands 'hostname' and 'pwd':

hostname is a command that displays the host name portion of the full computer name of the computer.

bash

pi@orangepi ~$ hostname
orangepi
pi@orangepi ~$

pwd is a command that stands for print working directory. It prints the path of the current working directory, starting from the root. The current working directory is the directory in which the user is currently working in.

bash

pi@orangepi ~$ pwd
/home/pi
pi@orangepi ~$

sudo (command) : This will give you the ability to execute commands as the superuser, also known as the root user or the administrator. The superuser has the highest level of privileges on the system and can perform tasks that are restricted for other users. For example, sudo apt update will update the list of available packages from the repositories, which requires superuser permissions. When you use sudo, you will be prompted to enter your password for authentication.

bash

pi@orangepi ~$ sudo apt update
[sudo] password for user: 
Hit:1 http://archive.ubuntu.com/ubuntu focal InRelease
Get:2 http://archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]
...

sudo -i : This will set sudo interactive mode, which means you will be logged in as the root user and can run multiple commands without typing sudo each time. You will still need to enter your password to start the interactive mode. To exit the interactive mode, type exit or press Ctrl+D. For example, sudo -i will log you in as the root user and then you can run commands like apt update and apt upgrade without sudo.

bash

pi@orangepi ~$sudo -i
[sudo] password for user: 
pi@orangepi:~# apt upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
...
pi@orangepi:~# exit
logout
pi@orangepi ~$

Navigating the filesystem

Basic commands

The cd command stands for change directory. It allows you to navigate to a different directory in the file system. You can specify the path of the directory you want to go to as an argument. For example, cd / will take you to the root directory, which is the topmost level of the file system. You can also use cd .. to go up one level in the directory hierarchy, or cd ~ to go to your home directory. Here is an example:

bash

pi@orangepi:~$ cd / # change to the root directory
pi@orangepi:/$ cd home # change to the home directory
pi@orangepi:/home$ cd orangepi # change to the orangepi directory
pi@orangepi:~$ cd .. # go up one level
pi@orangepi:/home$ cd ~ # go back to the home directory
pi@orangepi:~$

The ls command stands for list. It displays the files and directories in the current directory. You can also specify a different directory as an argument to list its contents. For example, ls / will list the files and directories in the root directory. The ls command has many options that can modify its output, such as -l for long format, -a for showing hidden files, -t for sorting by modification time, and -S for sorting by size. Here is an example of using the ls command with some options in a code block:

bash

pi@orangepi:~$ ls -l / # list the files and directories in the root directory in long format
total 72
drwxr-xr-x   2 root root  4096 Apr  6 11:54 bin
drwxr-xr-x   3 root root  4096 Apr  6 11:54 boot
drwxr-xr-x  15 root root  3180 Apr  6 11:54 dev
drwxr-xr-x  95 root root  4096 Apr  6 11:54 etc
drwxr-xr-x   3 root root  4096 Apr  6 11:54 home
drwxr-xr-x  18 root root  4096 Apr  6 11:54 lib
drwx------   2 root root 16384 Apr  6 11:54 lost+found
drwxr-xr-x   2 root root  4096 Apr  6 11:54 media
drwxr-xr-x   2 root root  4096 Apr  6 11:54 mnt
drwxr-xr-x   3 root root  4096 Apr  6 11:54 opt
dr-xr-xr-x 108 root root     0 Apr  6 11:54 proc
drwx------   4 root root  4096 Apr  6 11:54 root
drwxr-xr-x  21 root root   660 Apr  6 11:54 run
drwxr-xr-x   2 root root  4096 Apr  6 11:54 sbin
drwxr-xr-x   2 root root  4096 Apr  6 11:54 srv
dr-xr-xr-x  12 root root     0 Apr  6 11:54 sys
drwxrwxrwt   9 root root  4096 Apr  6 11:54 tmp
drwxr-xr-x  10 root root  4096 Apr  6 11:54 usr
drwxr-xr-x  11 root root  4096 Apr  6 11:54 var

cp (source) (dest) : This will copy the contents of the source file into a destination file. You can specify the path to the source and destination files as arguments, either as absolute paths or relative paths. For example, cp notes.txt backup will create a copy of notes.txt in the backup directory, while keeping the original file in the current directory.

bash

pi@orangepi:~$ cp notes.txt backup # copy notes.txt to backup directory
pi@orangepi:~$ ls backup # list the contents of backup directory
notes.txt

mv (filename) (directory) : This will move (essentially cut and paste) the file to the named directory. You can also use this command to rename a file by providing a new name as the destination. For example, mv report.pdf documents will move the file report.pdf from the current directory to the documents directory, and remove it from the current directory.

bash

pi@orangepi:~$ mv report.pdf documents # move report.pdf to documents directory
pi@orangepi:~$ ls documents # list the contents of documents directory
report.pdf

rm (filename) : This will remove the specified file. Be careful with this command, as there is no way to undo it. You can also use the -r option to remove a directory and its contents recursively. For example, rm old.txt will delete the file old.txt from the current directory.

bash

pi@orangepi:~$ rm old.txt # remove old.txt file
pi@orangepi:~$ ls # list the contents of current directory
backup  documents  new.txt

touch (filename) : This will create an empty file. You can also use this command to update the timestamp of an existing file. For example, touch new.txt will create a file named new.txt in the current directory, with no content and the current date and time as its timestamp.

bash

pi@orangepi:~$ touch new.txt # create new.txt file
pi@orangepi:~$ ls -l new.txt # show the details of new.txt file
-rw-r--r-- 1 pi pi 0 Jan 15 10:26 new.txt

mkdir (directory) : This will create a directory. You can use the -p option to create parent directories as needed. For example, mkdir projects will create a directory named projects in the current directory. mkdir -p projects/python/hello will create the directories projects, projects/python, and projects/python/hello if they do not exist.

bash

pi@orangepi:~$ mkdir projects # create projects directory
pi@orangepi:~$ ls # list the contents of current directory
backup  documents  new.txt  projects
pi@orangepi:~$ mkdir -p projects/python/hello # create projects/java/hello directory
pi@orangepi:~$ ls projects/python # list the contents of projects/java directory
hello

find / -name (filename) : This will search your whole computer for a file. You can use wildcards to match patterns. For example, find / -name settings.txt will look for a file named settings.txt in every directory and subdirectory starting from the root (/). find / -name "*.jpg" will find all files with the .jpg extension.

bash

pi@orangepi:~$ find / -name settings.txt # search for resume.docx file
/home/pi/Documents/settings.txt
pi@orangepi:~$ find / -name "*.jpg" # search for jpg files
/home/pi/Pictures/wallpaper.jpg
/home/pi/Pictures/photo.jpg

man (command) : This is the “manual.” This will show you detailed information about a specific command. You can use the arrow keys, the space bar, or the enter key to scroll through the manual page, and press q to quit. You can also use the / key to search for a keyword within the manual page, and press n to go to the next match, or N to go to the previous match. For example, man ls will show the manual page for the ls command, which lists the contents of a directory.

bash

pi@orangepi:~$ man ls # show the manual page for ls command
LS(1)                            User Commands                           LS(1)

NAME
       ls - list directory contents

SYNOPSIS
       ls [OPTION]... [FILE]...

DESCRIPTION
       List  information  about  the FILEs (the current directory by default).
       Sort entries alphabetically if none of -cftuvSUX nor --sort  is  speci‐
       fied.

       Mandatory  arguments  to  long  options are mandatory for short options
       too.

       -a, --all
              do not ignore entries starting with .

Common directories

Using the ls command reveals a lot of directories. An explanation of the most common ones:

/bin is the main executables folder. It contains essential binary files that are needed for the basic functioning of the system, such as bash, ls, cp, mv, etc. These files are usually executable by all users and are invoked by the shell or other programs .
/boot is the folder containing the pi boot config, FAT formatted partition can be edited on your PC. It contains the files that are required to boot the system, such as the kernel image, the bootloader, the device tree, and the initramfs. The boot config file (config.txt) can be used to customize various settings, such as the display resolution, the memory split, the overclocking, etc. The FAT formatted partition means that the files can be accessed by other operating systems, such as Windows, that can read the FAT file system .
/dev is the folder where the files in this folder are the devices in the system (unix sees everything as files in the system so /dev/eth0 is the ethernet port). It contains special files that represent the devices that are attached to the system, such as disks, terminals, printers, cameras, etc. These files can be used to communicate with the devices, either by reading from or writing to them. For example, /dev/eth0 is the file that represents the first ethernet interface, and /dev/sda is the file that represents the first SATA disk .
/etc is the folder that is usually used for system configuration files. You will need at some time to edit files in here. It contains various files that store the settings and preferences for the system and the applications that run on it. For example, /etc/passwd is the file that stores the user accounts and their information, /etc/fstab is the file that stores the mount points and options for the file systems, /etc/hostname is the file that stores the name of the system, etc. These files can be edited by the system administrator to change the behavior of the system or the applications .
/home is the folder that is usually used for the users on your Pi's home directories. When you login as orangepi you are put into the /home/orangepi folder which you can use to put your files. It contains the subdirectories that belong to each user that has an account on the system. These subdirectories are also called the home directories of the users, and they store their personal files, settings, and preferences. For example, /home/orangepi is the home directory of the user orangepi, and /home/pi is the home directory of the user pi. The users can create, modify, and delete files in their own home directories, but they may not have access to other users' home directories, depending on the permissions .
/lib is the folder that is usually used for system library files so is a bit like the c:\windows\system32 folder on your PC. It contains the shared library files that are needed by the binary files in /bin and /sbin to run. These library files provide common functions and features that are used by many programs, such as input/output, memory management, network communication, etc. For example, /lib/libc.so is the file that contains the standard C library, which is used by almost every program on the system .
/media and /mnt are the folders that are used for mounting storage devices. They are used to attach the file systems that are located on external devices, such as USB drives, CD-ROMs, network shares, etc., to the directory hierarchy of the system. For example, /media/pi/USB could be the mount point for a USB drive that belongs to the user pi, and /mnt/nas could be the mount point for a network-attached storage device. The difference between /media and /mnt is that /media is usually used for temporary or removable devices that are mounted automatically by the system, while /mnt is usually used for permanent or fixed devices that are mounted manually by the user .
/opt is the folder that is usually used for optional programs. It contains the subdirectories that store the files and directories of the applications that are not part of the standard distribution of the system, but are installed by the user or a third-party vendor. These applications are usually self-contained and do not interfere with the rest of the system. For example, /opt/firefox could be the subdirectory that contains the files and directories of the Firefox web browser, and /opt/minecraft could be the subdirectory that contains the files and directories of the Minecraft game .
/proc is the folder that usually shows information about processes, is a pseudo-filesystem. It contains the special files that provide information about the processes that are running on the system, as well as other system information, such as the CPU, the memory, the devices, etc. These files are not stored on the disk, but are generated dynamically by the kernel when they are accessed. For example, /proc/1 is the file that provides information about the process with the ID 1, which is usually the init process, and /proc/cpuinfo is the file that provides information about the CPU of the system .
/root is the home folder of the root user. It is where the system administrator can store their personal files and settings, as well as perform administrative tasks that require root privileges. The root user is the superuser that has full access and control over the system, and can perform any operation on any file or directory. The root user should be used with caution, as it can cause damage or instability to the system if used incorrectly .
/sbin is the folder where the system maintenance and/or administrative task programs are found. It contains the binary files that are used for system administration and maintenance, such as fdisk, ifconfig, mount, reboot, etc. These files are usually executable only by the root user or the users with sudo privileges, as they can affect the whole system or other users' files and directories .
/tmp is the folder for temporary files, you can use it but the files in it are deleted on system boot. It contains the files that are created and used by the programs that run on the system, but are not needed after the programs terminate. These files can be used for storing intermediate results, caching data, logging messages, etc. The files in /tmp are accessible by all users, but they are not persistent, as they are deleted when the system is rebooted or when the files are not accessed for a certain period of time .
/usr is the folder for user installed programs - quite often system shell programs are written and put in /usr/local/bin. It contains the subdirectories that store the files and directories of the applications that are installed by the user or the package manager, and are not essential for the basic functioning of the system. These applications are usually shared and used by multiple users, and do not require root privileges to run. For example, /usr/bin contains the binary files of the user applications, such as python, gcc, nano, etc., /usr/lib contains the library files of the user applications, such as /usr/lib/python3.7, /usr/lib/gcc, etc., and /usr/share contains the shared data of the user applications, such as /usr/share/doc, /usr/share/icons, etc. The /usr/local subdirectory is used for the applications that are installed locally by the user, and are not managed by the package manager. For example, /usr/local/bin contains the binary files of the local applications, such as pip, git, node, etc .
/var is the folder where variable data in the system is stored - such as logs/mail etc. It contains the subdirectories that store the files and directories that change frequently or dynamically, such as logs, caches, spools, databases, etc. These files are used to store the information that is generated or modified by the system or the applications that run on it. For example, /var/log contains the log files of the system and the applications, such as /var/log/syslog, /var/log/apache2, etc., /var/cache contains the cache files of the applications, such as /var/cache/apt, /var/cache/fontconfig, etc., and /var/mail contains the mail files of the users, such as /var/mail/orangepi, /var/mail/pi, etc .

Checking permissions

When you list the files and directories in the current directory in a long format, it also shows the permissions and other information of each file and directory. For example, ls -l will show something like this:

bash

pi@orangepi:~$ ls -l
total 32
drwxr-xr-x 2 pi pi 4096 Nov  2 10:23 backup
drwxr-xr-x 3 pi pi 4096 Nov  2 10:23 documents
-rw-r--r-- 1 pi pi    0 Jan 15 10:26 new.txt
drwxr-xr-x 3 pi pi 4096 Nov  2 10:23 projects

The first column shows the permissions of each file and directory. The permissions are composed of 10 characters, which can be divided into four parts:
- The first character indicates the type of the file or directory. It can be one of the following:
  - - : regular file
  - d : directory
  - l : symbolic link
  - c : character device
  - b : block device
  - p : named pipe
  - s : socket
  - ? : unknown type
- The next three characters indicate the permissions for the owner (user) of the file or directory. They can be one of the following:
  - r : read permission, which means the owner can read the contents of the file or list the contents of the directory.
  - w : write permission, which means the owner can modify the file or create, delete, or rename files in the directory.
  - x : execute permission, which means the owner can execute the file or enter the directory.
  - - : no permission, which means the owner cannot perform the corresponding action.
- The next three characters indicate the permissions for the group of the file or directory. They have the same meaning as the permissions for the owner, but they apply to the members of the group that has been assigned to the file or directory.
- The last three characters indicate the permissions for the others, which means anyone else who is not the owner or a member of the group. They have the same meaning as the permissions for the owner and the group, but they apply to all other users on the system.

For example, the permissions -rw-r--r-- mean that the file is a regular file, the owner can read and write it, the group can only read it, and the others can only read it. The permissions drwxr-xr-x mean that the file is a directory, the owner can read, write, and execute it, the group can only read and execute it, and the others can only read and execute it.

The other columns (1 pi pi 0 Jan 15 10:26 new.txt) show the following information:
- The number of hard links to the file or directory.
- The name of the owner of the file or directory.
- The name of the group of the file or directory.
- The size of the file or directory in bytes.
- The date and time of the last modification of the file or directory.
- The name of the file or directory.

Changing permissions

chmod : This command changes the permissions of files and directories. You can use different ways to specify the new permissions, such as numeric mode, symbolic mode, or reference mode. For example:

bash

pi@orangepi:~$ chmod u+x file # will give the user (owner) execute permission on the file
pi@orangepi:~$ chmod 755 dir # will give the user read, write, and execute permissions, and the group and others read and execute permissions on the directory
pi@orangepi:~$ chmod u=rwx,g=rx,o=rx file # will do the same as chmod 755 file

The numeric mode uses three digits to represent the permissions for the user, the group, and the others. Each digit is the sum of the values for each permission:

- `4` : read permission
- `2` : write permission
- `1` : execute permission
- `0` : no permission

For example, 7 means read, write, and execute permissions, 6 means read and write permissions, 5 means read and execute permissions, 4 means read permission, 3 means write and execute permissions, 2 means write permission, 1 means execute permission, and 0 means no permission.

The symbolic mode uses symbols to represent the permissions for the user (u), the group (g), the others (o), or all of them (a).

You can use the following operators to change the permissions:

+ : add the specified permissions to the existing permissions
- : remove the specified permissions from the existing permissions
= : set the specified permissions and clear the others

You can use the following symbols to represent the permissions:

r : read permission
w : write permission
x : execute permission

So, for example:

u+x means add execute permission for the user
g-w means remove write permission for the group
o=r means set read permission and clear the others for the others

Here are some more examples of how to use the chmod command:

To give read and write permissions to the user and the group, and no permissions to the others, on a file named secret.txt, you would use one of the two commands:

bash

pi@orangepi:~$ chmod 660 secret.txt
pi@orangepi:~$ chmod u=rw,g=rw,o= secret.txt

To give execute permission to everyone on a file named script.sh, you would use one of the two commands:

bash

pi@orangepi:~$ chmod a+x script.sh
pi@orangepi:~$ chmod 755 script.sh

To remove all permissions from a file named junk.txt, you would use one of the two commands:

bash

pi@orangepi:~$ chmod 000 junk.txt
pi@orangepi:~$ chmod a= junk.txt

To copy the permissions of a file named example.txt to a file named test.txt, you would use one of the two commands:

bash

pi@orangepi:~$ chmod --reference=example.txt test.txt

IP addressing commands

ip addr is a command that shows the IP address details of the interface of your pi. It can also be used to add, delete, or modify the IP addresses of the interfaces. For example, ip addr show eth0 will display the IP address of the ethernet interface, and ip addr add 192.168.1.100/24 dev eth0 will assign a static IP address of 192.168.1.100 to the ethernet interface.

The IP address details of the interface of the Pi

ip route is a command that shows the system routing table. It can also be used to add, delete, or modify the routes of the system. For example, ip route show will display the current routes, and ip route add default via 192.168.1.1 dev eth0 will add a default gateway of 192.168.1.1 to the ethernet interface.

more or nano are commands that allow you to read a text file. more is a simple pager that displays the contents of a file one screen at a time, and allows you to scroll down or search for a pattern. nano is a text editor that allows you to view and edit the contents of a file, and provides some basic features such as cut, paste, undo, search, and replace. For example, more /etc/resolv.conf will display the contents of the /etc/resolv.conf file, which is your host file that stores the DNS server addresses. nano /etc/resolv.conf will open the same file in the nano editor, where you can make changes and save them. Here is an example of the output of more /etc/resolv.conf:

# Generated by NetworkManager
nameserver 8.8.8.8
nameserver 8.8.4.4

Monitoring the system

date is a command that displays the current date and time of the system. It can also be used to set the system date and time, or to format the output in different ways. For example, date +"%A, %B %d, %Y" will display the date as Tuesday, March 5, 2024:

bash

pi@orangepi:~$ date +"%A, %B %d, %Y" 
Tuesday, March 5, 2024

df -h is a command that reports how much free disk space is available on the file systems. The -h option makes the output human-readable, by using units such as K, M, G, etc. For example, df -h / will display the disk usage of the root file system. Here is an example of the output of df -h /:

Sure, I can talk more about these commands and give you some examples. 😊

free -m is a command that displays the total amount of free and used physical and swap memory in the system, as well as the buffers and caches used by the kernel, in megabytes. The information is gathered by parsing /proc/meminfo. For example, free -m will show something like this:

bash

pi@orangepi:~$ free -m
              total        used        free      shared  buff/cache   available
Mem:           1987         654         320          13        1012        1158
Swap:          1535         119        1416

pstree -G is a command that shows the running processes as a tree, which is a more convenient way to display the processes hierarchy and makes the output more visually appealing. The root of the tree is either init or the process with the given pid. For example, pstree -G will show something like this:

bash

pi@orangepi:~$ pstree -G
systemd─┬─VBoxService───7*[{VBoxService}]
        ├─accounts-daemon───2*[{accounts-daemon}]
        ├─2*[agetty]
        ├─atd
        ├─cron
        ├─dbus-daemon
        ├─irqbalance───{irqbalance}
        ├─2*[iscsid]
        ├─lvmetad
        ├─lxcfs───2*[{lxcfs}]
        ├─networkd-dispat───{networkd-dispat}
        ├─nginx───2*[nginx]
        ...

sudo killall <name of process> is a command that kills all processes that match the name specified. Without additional arguments, killall sends SIGTERM, or signal number 15, which terminates running processes that match the name specified. For example, sudo killall sshd will kill all processes named sshd.

bash

$ sudo killall sshd

top is basically the task manager for Linux. It provides an ongoing look at processor activity in real time. It can sort the tasks by CPU usage, memory usage and runtime.

htop is similar to top but improved with graphs and color

dmesg shows the kernel logs since boot time.

You can specify this further, for example dmesg | grep usb just shows logs involving USB devices.

Installing packages

apt-get is a command-line tool that is used to manage packages on Debian-based systems, such as Ubuntu. It can install, remove, update, and upgrade packages from the repositories that are specified in the /etc/apt/sources.list file and the files in the /etc/apt/sources.list.d directory.

The options for this are:

install : to install packages and dependencies. For example, apt-get install gedit will install the gedit package.
remove : to remove packages and configuration files. For example, apt-get remove gedit will remove the gedit package.
update : to update the list of available packages from the repositories. For example, apt-get update will refresh the package list.
upgrade : to upgrade all the installed packages and OS to the latest versions. This usually takes about 20 minutes!

wget is a command-line tool that can download files from the web using various protocols, such as HTTP, HTTPS, FTP, and FTPS. It can also resume interrupted downloads, mirror websites, and use wildcards and filters. Wget is available for Linux, macOS, and Windows systems.

Some examples of wget usage are:

To download a single file from a URL, use:
wget http://example.com/file.zip
To download a file and save it with a different name, use the -O option:
wget -O new.zip http://example.com/file.zip
To download multiple files from a list of URLs in a text file, use the -i option:
wget -i urls.txt
To download a file in the background, use the -b option:
wget -b http://example.com/file.zip

Changing hostname and password

The system hostname is a name that is assigned to your device, it is used to identify your device on a network. It also can be appended to a domain.

If you want to ever change the system hostname again via bash, you will need to edit the file /etc/hostname as root. There will be just one line of code with the hostname.

So if you were to change by your own hostname to for example opi3:

bash

pi@orangepi:~$ sudo nano /etc/hostname

which should look like the entry below

bash

orangepi

and change it to opi3

Once you change the hostname you will run into a problem where every time you run a command with sudo you will get the error unable to resolve host “your hostname here” it means that the hostname does not match the IP of your PI.

You will need to edit the file /etc/hosts by executing the following command and changing the old hostname to your new hostname opi3.

bash

pi@orangepi:~$ sudo nano /etc/hosts

What to change on a /etc/hosts file of a Pi with old hostname opi23tvb

To then make the hostname active you must reboot the system

bash

pi@orangepi:~$ sudo reboot

Once the Pi has booted up and when you have logged back in, your prompt will have changed to

bash

pi@opi3:~$

You can also change the password for the current user, to do this:

Login to your Pi
Once you are logged into your Pi type the following command

bash

orangepi@orangepi:~# passwd

This command will prompt you to enter your current password and then a new password. You will need to confirm the new password by typing it again. This will change your password for the orangepi user account.

Type the following command to shut down the system and save the changes.

bash

orangepi@orangepi:~# sudo shutdown -h now

This command will use the sudo privilege to execute the shutdown command with the -h option, which means halt the system, and the now argument, which means do it immediately. This will power off your Pi safely.

Coding and running Python code on the Pi

In this section we will learn how to create a Python Hello-world program on our Pi:

python

# Hello world
print("Hello world!")

However, there are some challenges that we need to overcome. Our screen and keyboard are connected to our laptop, not the Pi. Our code has to run on the Pi, but our development environment also runs on our laptop.

This is called a headless setup, meaning that we can control the Pi without a monitor, keyboard, or mouse directly connected to it.

We will look at three ways steps to code and get our code on the Pi to run:

Do the upload manually, by copying the code from our laptop to the Pi using WinSCP and then using SSH to run the code.
Setup an automated pipeline, by using VSCode to open a local directory that you wish to sync between our laptop and the Pi whenever we make changes.
Work remotely on the Pi, by using either Vscode or VNC to access the Pi's desktop and terminal from our laptop. This way, we can edit, run, and debug the code on the Pi as if we were using it directly.

After this we will also look at some ways to backup your code.

Manually uploading Python code and running it via SSH

The advantages and disadvantages of this are:

✅ It works with any editor or IDE
✅ You have total control over the workflow
❌ You have to re-upload after every code change

In this way of working we will:

Program everything on your laptop
Use WinSCP to copy the files to the OPI (drag-and-drop) with the SFTP protocol
Use SSH to run the program code once it is on the Pi

Coding a basic Python file can be done in any IDE or editor. If you were to do it in Notepad++ you need to make sure to use the Unix format:

After saving the file locally on your laptop, the next step is to transfer it to the Pi. For this we will use WINSCP, download and install it on your laptop.

Using WINSCP you need to log in to the Pi with the correct credentials. Use the IP and the SSH port 22 of the Pi as we are using the SFTP protocol.

Establish a connection with the Pi on WINSCP

TIP

SFTP stands for SSH File Transfer Protocol. It is a network protocol that provides file access, file transfer, and file management over any reliable data stream. It is often used as a subsystem of SSH protocol version 2, which provides secure communication between computers. SFTP is more secure and versatile than FTP, which is an older protocol for file transfer. SFTP can also resume interrupted transfers, support all UNIX file types, and perform remote file removal.

Transfer the source file hello.py file from your local directory to the PI directory /home/orangepi.

All that is left now is to for example use PuTTY to enter the command to run the Python file. Be sure to move to the correct directory when doing this.

bash

pi@orangepi:~$ sudo python3 hello.py
hello world

Automated sync with VSCode for a directory with Python code

The advantages and disadvantages of this are:

✅ Automatic saving
✅ Automatic backup (files stored locally and remote)
❌ You still need run the code via an SSH tool, such as PuTTY or via ssh pi@192.168.0.x in PowerShell

In this way of working we will:

Install VSCode and use it to code a Python file
Install an SFTP VSCode extension and use it to automatically sync
Use SSH to run the program code once it is on the Pi

First off download and install VSCode. After installing, use it to open a folder where you will be saving your Python file(s) and code the file. Upon saving, VSCode may ask you to install the python-plugins. Do so.

python

# Hello world
print("Hello world!")

Go to the "Extensions" tab on the left ribbon and search for the SFTP extension.

After installing open the VSCode command palette (Ctrl + Shift + p ) and type SFTP. Select SFTP: Config

This will generate a configuration file in a hidden .vscode-folder. Edit the settings in this file for your own Pi setup. You can leave the password out to be safer, but this will mean that you have to type it every time when saving.

The SFTP Config file edited with settings

After setting this up you can save the Python file again and notice the successful upload in the bottom of VSCode.

A successful upload with the SFTP extension

You can also optionally right-click in the coding pane and select upload file (to Pi) or download file (from Pi).

Working remotely on the Pi using VSCode

The advantages and disadvantages of this are:

✅ Really fluent workflow, once set up there is not much more work to it
✅ No errors when using libraries that aren’t installed on your laptop (like when using GPIO or other Pi specific libraries)
✅ Debugging is possible (breakpoints, stepping through code, variable monitoring)
❌ The only copy of your scripts is on the Pi, so be sure to back them up

TIP

You can also do this using PyCharm

In this way of working we will:

Install VSCode and install the VSCode Remote Extensionpack
Setup the SSH configuration to connect to our Pi host
Open folders on the Pi, code the Python file directly on the Pi and run it with the Pi bash

First off download and install VSCode.

After that go to the "Extensions" tab on the left ribbon and search for the Remote - SSH extension.

After installing, click the green arrow button on the bottom left of VSCode.

If the green arrow Remote SSH icon is missing:

Right click the activity bar and activate Remote Host

In the menu that opens, choose Open SSH configuration file. Here you need to add the IP or hostname of your Pi and the username your are using on your Pi (in lowercase!). If there is an error about the fingerprint having changed you also need to also remove the old host in C:/Users/your_user/.ssh/known_hosts file.

After doing that:

Click the green arrow-button on the bottom left again
In the menu that opens choose “Connect to Host…”. A new window opens.
Choose “Linux” in the menu that opens
Accept the fingerprint
Enter your password
Wait. It takes a long while the first time, but is a lot faster after that.

After this your VSCode enviroment should be connected to your Pi and you should now be able to see the Pi bash and open a folder:

Click the top Explorer 📄 tab icon on the left ribbon
Click Open Folder
Enter your password again

Coding Python directly on the Pi using VSCode

Note how you see the folders in your home-drive on the Pi. Now you can create a folder for files, create files and run them right on the Pi via bash. The extensions you have installed in VSCode on your laptop aren’t installed here so install the Python extension again to run Python files from VSCode.

To start developing again after you closed VSCode:

Click the green button
Choose the right host
Enter your password
Open the folder
Enter your password again

TIP

If you want to avoid having to type your password every time you start developing again you can save your Workspace in VSCode and store host keys.

Instructions are located at this link and under steps 4 and 5 at this link.

In short you will:

Check C:\Users\your_user.ssh\id_rsa.pub to see if you have already generated a local SSH key pair (private/public) on your laptop.
- If they are not there use the PowerShell command: ssh-keygen -t rsa -b 4096
- If OpenSSH is not installed look here.
Use PowerShell to copy the local public key to the SSH host Pi:

powershell

$USER_AT_HOST="your-user-name-on-host@hostname" 
$PUBKEYPATH="$HOME\.ssh\id_rsa.pub" 

$pubKey=(Get-Content "$PUBKEYPATH" | Out-String); ssh "$USER_AT_HOST" "mkdir -p ~/.ssh && chmod 700 ~/.ssh && echo '${pubKey}' >> ~/.ssh/authorized_keys && chmod 600 ~/.ssh/authorized_keys"

Lastly you can also use your VNC connection to work remotely on the Pi. In this case you will use a local editor on the Pi. This is however not used in a professional environment.

Backing up your code

Backing up your code is essential to not meet any unfortunate surprises. We will cover three options:

WinSCP
Git
USB stick

Back up files with WINSCP

Download and install WINSCP on your laptop if you haven't already. Using WINSCP you need to log in to the Pi with the correct credentials. Use the IP and the SSH port 22 of the Pi as we are using the SFTP protocol.

After that you can use the drag-an-drop interface to copy files between your laptop and the Pi.

Back up files with Git from the Pi

You have already used Git last semester, if you need a reminder visit the course site .

To back up files using Git from the Pi we need to first log in to the Pi, install and configure Git:

bash

pi@orangepi:~$ sudo apt-get update
pi@orangepi:~$ sudo apt-get install git ssh

pi@orangepi:~$ git config --global user.email "you@example.com"
pi@orangepi:~$ git config --global user.name "Your Name"

Then we need to set up credientials using SSH keys:

Generate a private-public keypair on the Pi

bash

pi@orangepi:~$ ssh-keygen

Navigate to “/home/orangepi/.ssh”, notice the 2 files
- id_rsa (private key, never ever share)
- id_rsa.pub (this one needs to be copied to github)

After that we need to log on to Github and go to https://github.com/settings/keys to add an SSH key. To get this key you need to access the aformentioned id_rsa.pub file using the cat id_rsa.pub command. Copy the displayed text and paste it in the browser.

Then create a new repository on Github where you want to save your file(s). Once created, select SSH in the menu and copy the URL.

Back on your Pi, navigate to a folder where you want to save the files and clone the repo.

bash

pi@orangepi:~$ git clone <the_url_you_copied>
pi@orangepi:~$ cd <your_repo_name>

From here on you can use Git as you usually would for other programming projects, now just from your Pi.

In case you are using VSCode to work remotely on the Pi, and are connected to it, you can use the built-in interface for Git as well. If you open the folder you cloned and create or copy in files, you will see a blue 1 appear in the side ribbon. You can click on this to use the built-in interface.

Using the Git built-in interface while working remote on the Pi

Back up files using a USB stick

Using a USB stick to back up files is a classic way of working. Do however notice that you should not actively work on the USB stick, use it to back up files.

First of all you should where the Pi system locates the USB device. With the USB device not plugged in, type:

bash

pi@orangepi:~$ sudo tail -f /var/log/messages

Then plug in the USB and look at the new lines that appear.

Press CTRL-C to stop the tail log tracking command. In this case the usb stick id is sda1. That means the USB device is located at /dev/sda1.

Alternatively, you can use this command when the USB stick is plugged in:

bash

pi@orangepi:~$ sudo fdisk -l

Now that we know where the USB device is located at we need to create a directory to mount the USB drive to with read-write rw access.

bash

pi@orangepi:~$ sudo mkdir /media/usbstick
pi@orangepi:~$ sudo mount -f vfat -o rw /dev/sda1 /media/usbstick

Now that the folder is mounted to the USB stick, writing to the directory will write the the USB stick and vice-versa. It is as if /media/usbstick is now the USB stick.

After copying your files to the directory you still need to unmount the USB stick again before pulling it out.

bash

pi@orangepi:~$ sudo unmount /media/usbstick

If the unmount command says the stick is in use, you may have to close any programs using the stick. Or if the current directory is /media/usbstick simply change it to another directory and then unmount the stick.

Refresher on bash with Orange Pi specifics ​

Navigating the filesystem ​

Basic commands ​

Common directories ​

Checking permissions ​

Changing permissions ​

IP addressing commands ​

Monitoring the system ​

Installing packages ​

Changing hostname and password ​

Coding and running Python code on the Pi ​

Manually uploading Python code and running it via SSH ​

Automated sync with VSCode for a directory with Python code ​

Working remotely on the Pi using VSCode ​

Backing up your code ​

Back up files with WINSCP ​

Back up files with Git from the Pi ​

Back up files using a USB stick ​

Refresher on bash with Orange Pi specifics

Navigating the filesystem

Basic commands

Common directories

Checking permissions

Changing permissions

IP addressing commands

Monitoring the system

Installing packages

Changing hostname and password

Coding and running Python code on the Pi

Manually uploading Python code and running it via SSH

Automated sync with VSCode for a directory with Python code

Working remotely on the Pi using VSCode

Backing up your code

Back up files with WINSCP

Back up files with Git from the Pi

Back up files using a USB stick