linux - getpwnam (3)
NAME
       getpwnam, getpwuid - get password file entry
SYNOPSIS
       #include <pwd.h>
       #include <sys/types.h>

       struct passwd *getpwnam(const char * name));

       struct passwd *getpwuid(uid_t uid));
DESCRIPTION
       The  getpwnam()  function returns a pointer to a structure
       containing  the  broken  out  fields  of   a   line   from
       /etc/passwd for the entry that matches the user name name.

       The getpwuid() function returns a pointer to  a  structure
       containing   the   broken   out  fields  of  a  line  from
       /etc/passwd for the entry that matches the user uid uid.

       The passwd structure is defined in <pwd.h> as follows:

              struct passwd {
                      char    *pw_name;       /* user name */
                      char    *pw_passwd;     /* user password */
                      uid_t   pw_uid;         /* user id */
                      gid_t   pw_gid;         /* group id */
                      char    *pw_gecos;      /* real name */
                      char    *pw_dir;        /* home directory */
                      char    *pw_shell;      /* shell program */
              };
RETURN VALUE
       The getpwnam() and getpwuid() functions return the  passwd
       structure,  or  NULL if the matching entry is not found or
       an error occurs.
ERRORS
       ENOMEM Insufficient memory to allocate passwd structure.
FILES
       /etc/passwdpassword database file
CONFORMING TO
       SVID 3, POSIX, BSD 4.3
SEE ALSO
       fgetpwent(3),   getpwent(3),   setpwent(3),   endpwent(3),
       getpw(3), putpwent(3)