Getting the user's local username

Hi all,

I'm trying to write a program in a Linux enviroment that parses through some xml files, that reside in the user's home dir. The problem is getting that user's username, so I can put together the path to those files (e.g. /home/username/.hiddendir/file.xml).

I've looked as much as I can, but can't find a way to dynamically, during program execution, get the user's username on the OS. Does anyone know how this could be done?

use the path ~/.hiddendir/file.xml

~ is a symbolic link to the user's home directory.

Of course. Stupid me. Thanks, works nicely now :)

I don't think fopen() handles ~ expansion:

Code:

---

itsme@itsme:~/C$ cat homediropen.c
#include <stdio.h>

int main(void)
{
  FILE *fp;

  if(!(fp = fopen("~/garbage.txt", "r")))
    puts("Couldn't open file");
  else
  {
    puts("File opened successfully");
    fclose(fp);
  }

  return 0;
}

---

Code:

---

itsme@itsme:~/C$ ls ~/garbage.txt
/home/itsme/garbage.txt
itsme@itsme:~/C$ ./homediropen
Couldn't open file
itsme@itsme:~/C$

---

This does seem to work though:

Code:

---

itsme@itsme:~/C$ cat homediropen.c
#include <stdio.h>
#include <stdlib.h>

int main(void)
{
  FILE *fp;
  char *homedir;
  char filename[BUFSIZ];

  if(!(homedir = getenv("HOME")))
  {
    puts("Environment variable HOME not available");
    return 1;
  }

  sprintf(filename, "%s/garbage.txt", homedir);

  if(!(fp = fopen(filename, "r")))
    puts("Couldn't open file");
  else
  {
    puts("File opened successfully");
    fclose(fp);
  }

  return 0;
}

---

Code:

---

itsme@itsme:~/C$ ./homediropen
File opened successfully
itsme@itsme:~/C$

---

Quote:

---

Originally Posted by Datamike

Of course. Stupid me. Thanks, works nicely now :)

---

Using ~ worked for you? :eek:

Quote:

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Originally Posted by itsme86

Using ~ worked for you? :eek:

---

Actually, no, it didn't. Thought at first that it had worked, since I got no errors from my program. But that just turned out to be a bug in my code. The code you posted, worked though, so I've been able to continue my project. Thank you for that. :)

Oh yeah ~ must be a shell thing. It's been ages since I've used Unix.

Yes, it's only the shell that knows what to do with ~.

What you need to do is use getuid() to find out the user id number of the person running the program, then getpwuid to grab the attributes including home directory:

Code:

---

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <pwd.h>

int main(void)
{
    struct passwd *p;
    p = getpwuid(getuid());
    printf("Your home dir is %s\n", p->pw_dir);
    return 0;
}

/* my output:
Your home dir is /usr/home/cwr
*/

---

P.S. The Linux Programming forum is an excellent place for questions related to Linux programming. :p

Quote:

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Originally Posted by cwr

P.S. The Linux Programming forum is an excellent place for questions related to Linux programming. :p

---

Cool :cool:
Thanks for the advice, I'll try it out :)