getenv("HOME") returns "/root" with "sudo"

Question

I'm writing a program on my Raspberry Pi that requires the function "getenv("HOME")" to locate "/home/pi".

However, since I'm using the "wiringPi" library that requires "sudo" to run, "getenv("HOME")" now returns "/root" as the HOME directory instead of "/home/pi".

Is there a way to locate "/home/pi" with "getenv("HOME")" while using "sudo" the run the program?

Any help will be appreciated. Thank you.

If you know the answer is `/home/pi`, why do you need `getenv("HOME")` to get the wrong value? Presumably, calling `setenv("HOME", "/home/pi", 1)` is a bit too much like cheating, too? Why are you sure that the value you need is `/home/pi`? Why isn't `/root` correct when the program is run by `root` (or someone running `sudo`)? — Jonathan Leffler, Mar 12 '15 at 02:59
There are many things you could do, including adding a command line option to your program to override use of `$HOME`, setting `$HOME` before running your program, looking first for a `$HOME_OVERRIDE` variable etc.. — Tony Delroy, Mar 12 '15 at 03:01
It's because "getenv("HOME")" is the code from another library I am trying to run, which I cannot change. **setenv("HOME", "/home/pi", 1)** works for me, thanks @Jonathan Leffler. — K.Y. L, Mar 12 '15 at 03:32

score 1 · Accepted Answer · answered Mar 12 '15 at 03:40

^{Transferring comments and response into an answer.}

If you know the answer is /home/pi, why do you need getenv("HOME") to get the wrong value?

It's because getenv("HOME") is the code from another library I am trying to run, which I cannot change.

Presumably, calling setenv("HOME", "/home/pi", 1) is a bit too much like cheating, too?

setenv("HOME", "/home/pi", 1) works for me.

~~Why are you sure that the value you need is /home/pi? Why isn't /root correct when the program is run by root (or someone running sudo)?~~

This becomes mostly immaterial given that there's another unchangeable library involved.

In that case, setting the correct value for the environment variable before invoking the other library is a mostly reasonable mechanism.

getenv("HOME") returns "/root" with "sudo"

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