dotnet-install.sh not adding dotnet command on Ubuntu

Question

I am not a Linux user so this might be a easy fix but I have tried the following:

1. first I install it using the command curl -sSL https://dot.net/v1/dotnet-install.sh | bash /dev/stdin for which I get the following result:

dotnet-install: .NET Core SDK version 2.1.403 is already installed. dotnet-install: Adding to current process PATH:
/home/<!username!>/.dotnet. Note: This change will be visible only when sourcing script. dotnet-install: Installation finished successfully.

2. I do . ~/.profile to reload the profile, but even after this when I run dotnet I get the following error:

Command 'dotnet' not found, but can be installed with: sudo snap install dotnet-sdk`

I was expecting the script to do everything and make dotnet available.

Answer 1

TLDR: curl | bash can not modify PATH so it will not add dotnet to your PATH. You need to add dotnet to your path manually. Add export PATH="$PATH:/home/<!username!>/.dotnet" to your ~/.profile (or ~/.bashrc or equivalent) and log out and log back in.

Long version:

When you run a command in the shell (for example, bash), the shell tries to find an executible with the name in the all the paths listed in the environment variable PATH. PATH is generally set to something like /bin:/usr/bin. So when you type a command like curl, your shell looks in both /bin and /usr/bin for an executible file named curl.

You can see what your PATH is by doing env | grep PATH or echo $PATH.

The other important piece of information is how environment variables propagate. It's quite simple, actually:

1. A program (or process) can only modify its own set of environment variables.
2. Any child processes that a process creates inherit its environment variables.

What this means is that a program that you execute can not modify the environment variables of another random program. The shell actually provides a special command, export to set its own environment variables (and any child processes it later creates will inherit those).

Note the output at the end of step 1.

Note: This change will be visible only when sourcing script.

If you run curl | bash, it runs bash as a child process. That child process can not modify the environment variables of the program that started it (the shell that invoked curl | bash). So it can not modify PATH to add the location of dotnet to it. It even (helpfully) tells you that it can't.

In step 2, you are reloading ~/.profile. But does it contain any commands to add dotnet to PATH? I dont think so. I know the dotnet-install.sh script has not historically added it. You need to add a line like

export PATH="$PATH:/home/<!username!>/.dotnet"

To your ~/.profile (or ~/.bashrc, or equivalent) manually.

Actually, I would write it as follows to make the change more portable to other users:

export PATH="$PATH:$HOME/.dotnet"