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Full Discussion: Help with getuid
Top Forums Programming Help with getuid Post 302893878 by Corona688 on Friday 21st of March 2014 12:07:27 PM
Old 03-21-2014
getuid is a kernel call which returns a number the process already had -- every process has a user. Looking up other users means opening /etc/passwd, which means using a library call like getpname, which searches the name, or getpwent, which loops over the entire /etc/passwd file.

Note that some of the fields in the structure it returns are obsolete -- especially password, which is now stored elsewhere.

Code:
#include <sys/types.h>
#include <pwd.h>
#include <stdio.h>

int main(void) {
        const char *user="user";
        struct passwd *p=getpname(user);

        if(p != NULL)
                printf("name %s UID %d GID %d\n", (int)p->pw_name, p->pw_uid, (int)p->pw_gid);
        else fprintf(stderr, "No such user '%s'\n", user);
}

 

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LEARN ABOUT OSF1

getuid

getuid(2)							System Calls Manual							 getuid(2)

NAME

       getuid, geteuid - Gets the real or effective user ID

SYNOPSIS

       #include <unistd.h>

       uid_t getuid( void );

       uid_t geteuid( void );

       Application  developers	may  want  to  specify an #include statement for <sys/types.h> before the one for <unistd.h> if programs are being
       developed for multiple platforms. The additional #include statement is not required on Tru64 UNIX systems or by ISO  or	X/Open	standards,
       but may be required on other vendors' systems that conform to these standards.

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       getuid():  POSIX.1, XPG4, XPG4-UNIX

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

DESCRIPTION

       The getuid() function returns the real user ID of the calling process.

       The geteuid() function returns the effective user ID of the calling process.

RELATED INFORMATION

       Functions: setuid(2), setruid(3), setreuid(2)

       Standards: standards(5) delim off

																	 getuid(2)
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