tl;dr version
I added:
PKG_CONFIG_PATH="/usr/lib/pkgconfig:/usr/share/pkgconfig:/usr/lib/x86_64-linux-gnu"
to ~/.profile and saved the file, closed and re-opened Terminal and echo $PKG_CONFIG_PATH gave me a blank line.
Details
I am very new to Linux and Ubuntu.
I am using Terminal to run cargo install cargo-embed. I got an error:
Unable to find libudev:
pkg-config exited with status code 1
> PKG_CONFIG_ALLOW_SYSTEM_LIBS=1 PKG_CONFIG_ALLOW_SYSTEM_CFLAGS=1 pkg-config --libs --cflags libudev
The system library libudev required by crate hidapi was not found.
The file libudev.pc needs to be installed and the PKG_CONFIG_PATH environment variable must contain its parent directory.
The PKG_CONFIG_PATH environment variable is not set.
HINT: if you have installed the library, try setting PKG_CONFIG_PATH to the directory containing libudev.pc.
I have installed the library so I tried to set PKG_CONFIG_PATH.
First, I ran echo $PKG_CONFIG_PATH to confirm and got a blank line.
Then I ran gedit ~/.profile as suggested in an answer about setting environment variables permanently. At the end of the file, I added:
PKG_CONFIG_PATH="/usr/lib/pkgconfig:/usr/share/pkgconfig:/usr/lib/x86_64-linux-gnu"
and saved the file. I then ran source ~/.profile and re-ran echo $PKG_CONFIG_PATH to confirm and got
/usr/lib/pkgconfig:/usr/share/pkgconfig:/usr/lib/x86_64-linux-gnu
I then accidentally closed the terminal window and when I opened a new one and tried cargo install cargo-embed I got the same error. I ran echo $PKG_CONFIG_PATH again and got a blank line.
If I run source ~/.profile it imports but when I close and re-open Terminal it's not there. I tried just adding echo "Test" near the start of the .profile file to see if it's running. I see it when I run source ~/.profile but I don't see it when I open the Terminal. But then I don't know if I should see it. Like, I said, I'm very new to Ubuntu
Clarification
I have got past the cargo installation problem. I'd still like to know why this didn't work and how to add an environment variable permanently.
