How to get the username in C/C++ in Linux?

c++ c linux posix username
Zat42 picture Zat42 · Jan 21, 2012 · Viewed 85.3k times · Source

How can I get the actual "username" without using the environment (getenv, ...) in a program?

Answer

drrlvn picture drrlvn · Jan 21, 2012

The function getlogin_r() defined in unistd.h returns the username. See man getlogin_r for more information.

Its signature is:

int getlogin_r(char *buf, size_t bufsize);

Needless to say, this function can just as easily be called in C or C++.

Related questions

Is there an equivalent to WinAPI's MAX_PATH under linux/unix?

If I want to allocate a char array (in C) that is guaranteed to be large enough to hold any valid absolute path+filename, how big does it need to be. On Win32, there is the MAX_PATH define. What …

Read More
Linux 3.0: Executing child process with piped stdin/stdout

Under Linux 3.0 / C++: I would like a function that does the following: string f(string s) { string r = system("foo < s"); return r; } Obviously the above doesn't work, but you get the idea. I have a string s that …

Read More
Easily measure elapsed time

I am trying to use time() to measure various points of my program. What I don't understand is why the values in the before and after are the same? I understand this is not the best way to profile my …

Read More