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NAME

       getpwent_r, fgetpwent_r - get passwd file entry reentrantly

SYNOPSIS

       #include <pwd.h>

       int getpwent_r(struct passwd *pwbuf, char *buf,
                      size_t buflen, struct passwd **pwbufp);

       int fgetpwent_r(FILE *fp, struct passwd *pwbuf, char *buf,
                       size_t buflen, struct passwd **pwbufp);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getpwent_r(), _BSD_SOURCE || _SVID_SOURCE
       fgetpwent_r(): _SVID_SOURCE

DESCRIPTION

       The functions getpwent_r() and fgetpwent_r() are the reentrant versions
       of getpwent(3) and fgetpwent(3).  The  former  reads  the  next  passwd
       entry from the stream initialized by setpwent(3).  The latter reads the
       next passwd entry from the stream fp.

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

           struct passwd {
               char    *pw_name;      /* username */
               char    *pw_passwd;    /* user password */
               uid_t    pw_uid;       /* user ID */
               gid_t    pw_gid;       /* group ID */
               char    *pw_gecos;     /* user information */
               char    *pw_dir;       /* home directory */
               char    *pw_shell;     /* shell program */
           };

       For more information about the fields of this structure, see passwd(5).

       The nonreentrant functions return a pointer to  static  storage,  where
       this  static  storage contains further pointers to user name, password,
       gecos  field,  home  directory  and  shell.   The  reentrant  functions
       described here return all of that in caller-provided buffers.  First of
       all there is the buffer pwbuf that can hold a struct passwd.  And  next
       the  buffer  buf  of size buflen that can hold additional strings.  The
       result of these functions, the struct passwd read from the  stream,  is
       stored  in  the  provided  buffer  *pwbuf, and a pointer to this struct
       passwd is returned in *pwbufp.

RETURN VALUE

       On success, these functions return 0 and *pwbufp is a  pointer  to  the
       struct  passwd.   On  error,  these functions return an error value and
       *pwbufp is NULL.

ERRORS

       ENOENT No more entries.

       ERANGE Insufficient buffer  space  supplied.   Try  again  with  larger
              buffer.

CONFORMING TO

       These  functions  are  GNU  extensions,  done in a style resembling the
       POSIX version of  functions  like  getpwnam_r(3).   Other  systems  use
       prototype

           struct passwd *
           getpwent_r(struct passwd *pwd, char *buf, int buflen);

       or, better,

           int
           getpwent_r(struct passwd *pwd, char *buf, int buflen,
                      FILE **pw_fp);

NOTES

       The  function  getpwent_r() is not really reentrant since it shares the
       reading position in the stream with all other threads.

EXAMPLE

       #define _GNU_SOURCE
       #include <pwd.h>
       #include <stdio.h>
       #define BUFLEN 4096

       int
       main(void)
       {
           struct passwd pw, *pwp;
           char buf[BUFLEN];
           int i;

           setpwent();
           while (1) {
               i = getpwent_r(&pw, buf, BUFLEN, &pwp);
               if (i)
                   break;
               printf("%s (%d)\tHOME %s\tSHELL %s\n", pwp->pw_name,
                      pwp->pw_uid, pwp->pw_dir, pwp->pw_shell);
           }
           endpwent();
           exit(EXIT_SUCCESS);
       }

SEE ALSO

       fgetpwent(3),   getpw(3),   getpwent(3),   getpwnam(3),    getpwuid(3),
       putpwent(3), passwd(5)

COLOPHON

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       description of the project, and information about reporting  bugs,  can
       be found at http://man7.org/linux/man-pages/.