topic Can I find a users home directory from within a c program? in Operating System - HP-UX

Can I find a users home directory from within a c program?

Renda Skandier — Thu, 06 Oct 2005 10:51:50 GMT

Hi,
Seems like there should be an easy way to find the home directory of the user running the c program. The only way I can think of is to read an external file containing it.
Any ideas?
tia Renda

Re: Can I find a users home directory from within a c program?

Mel Burslan — Thu, 06 Oct 2005 10:54:22 GMT

I am not a c programmer but here is how you determine it in shell scripting:

USER=some_user_name
HOMEDIR=`grep $USER /etc/passwd | cut -d: -f6`

Hope this helps

Re: Can I find a users home directory from within a c program?

Alan Sengillo_1 — Thu, 06 Oct 2005 11:42:01 GMT

Use getpwnam() to get the password entry. Use the field pw_dir in the password entry for the home directory.

struct passwd *passwordEntry;

passwordEntry = getpwnam ("user account name goes here");

passwordEntry->pw_dir /* Home directory */

Re: Can I find a users home directory from within a c program?

Volker Borowski — Thu, 06 Oct 2005 13:05:34 GMT

I am not a tight programmer,
but I would have thought of accessing the environment variable "~", but I think the getpasswd solution is more elegant.
It just might not work in case you need to use a s-uid bit on your program ?
Would you receive the HOME of the s-bit owner in this case, or the password-entry of the real user ?
This is more a question to Alan than a solution for you, so no points please.
Thanks
Volker

Re: Can I find a users home directory from within a c program?

A. Clay Stephenson — Thu, 06 Oct 2005 13:07:18 GMT

The getpwnam(0 function is a good approach. Another is simply

#include

char *home = NULL;
home = getenv("HOME");
if (home != NULL)
{
(void) printf("Homedir: %s\n",home);
}
else
{
(void) fprintf(stderr,"getenv() failed\n");
}

You should note that getenv() uses a static buffer so subsequent calls will overwrite the buffer even if used to getenv("MYVAR"), for example. This means that *home will suddenly change to whatever "MYVAR" was set to. As with all functions of this type, you should copy the thingy to another vaiable if subsequent getenv() calls are expected.
This same fixed-buffer design is used by getpwnam() as well so ...

Re: Can I find a users home directory from within a c program?

Alan Sengillo_1 — Thu, 06 Oct 2005 13:17:12 GMT

You pass the login name of the account to getpwnam() so the s-bit would not have any effect on the call.

Re: Can I find a users home directory from within a c program?

Renda Skandier — Thu, 06 Oct 2005 13:28:06 GMT

thanks... getenv is actually what I was thinking of but couldn't remember.

getpwnam looks like ti would work but not all user have access

Re: Can I find a users home directory from within a c program?

Tom Danzig — Thu, 06 Oct 2005 13:40:55 GMT

You could also make use of the system() function and the ~user substitution

system("echo ~root");

returns the home directory of root.