SAS/C Library Reference, Vol. 1

getlogin -- Determine User Login Name

SYNOPSIS

 #include <unistd.h>

 char *getlogin(void);

DESCRIPTION

getlogin returns the login name for the current process. Under OpenEdition MVS, this is the same as the userid defined for the batch job or TSO session that generated the process. The name string is stored in a static area and may be overwritten by subsequent calls to getlogin. The getlogin function fails if OpenEdition is not active or installed.

RETURN VALUE

getlogin returns a pointer to the name string if successful, and a NULL pointer if unsuccessful.

EXAMPLE

This example tests to see if the effective user ID is the ID belonging to the login name.

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

  main() {
     char *name;
     struct passwd *unifo;

     name = getlogin();
     if (!name) {
        perror("getlogin failure");
        exit(EXIT_FAILURE);
     }
     unifo = getpwnam(name);
     if (!unifo) {
        perror("getpwnam failure");
        exit(EXIT_FAILURE);
     }
     if (unifo->pw_uid == geteuid())
        puts("Your user ID number matches the effective user ID.");
     else
        puts("Your user ID does not match the effective user ID.");
     exit(EXIT_SUCCESS);
  }

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