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man:getpwent

GETPWENT(3) Linux Programmer's Manual GETPWENT(3)

NAME

     getpwent, setpwent, endpwent - get password file entry

SYNOPSIS

     #include <sys/types.h>
     #include <pwd.h>
     struct passwd *getpwent(void);
     void setpwent(void);
     void endpwent(void);
 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
     getpwent(), setpwent(), endpwent():
         _XOPEN_SOURCE >= 500
             || /* Glibc since 2.19: */ _DEFAULT_SOURCE
             || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

     The getpwent() function returns a pointer to a structure containing the
     broken-out fields of a record from the  password  database  (e.g.,  the
     local  password file /etc/passwd, NIS, and LDAP).  The first time getp-
     went() is called, it returns the first entry;  thereafter,  it  returns
     successive entries.
     The  setpwent() function rewinds to the beginning of the password data-
     base.
     The endpwent() function is used to close the  password  database  after
     all processing has been performed.
     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).

RETURN VALUE

     The getpwent() function returns a pointer to  a  passwd  structure,  or
     NULL  if  there  are no more entries or an error occurred.  If an error
     occurs, errno is set appropriately.  If one wants to check errno  after
     the call, it should be set to zero before the call.
     The  return value may point to a static area, and may be overwritten by
     subsequent calls to getpwent(), getpwnam(3), or getpwuid(3).   (Do  not
     pass the returned pointer to free(3).)

ERRORS

     EINTR  A signal was caught; see signal(7).
     EIO    I/O error.
     EMFILE The per-process limit on the number of open file descriptors has
            been reached.
     ENFILE The system-wide limit on the total number of open files has been
            reached.
     ENOMEM Insufficient memory to allocate passwd structure.
     ERANGE Insufficient buffer space supplied.

FILES

     /etc/passwd
            local password database file

ATTRIBUTES

     For   an   explanation   of   the  terms  used  in  this  section,  see
     attributes(7).
     +------------+---------------+-----------------------------+
     |Interface   | Attribute     | Value                       |
     +------------+---------------+-----------------------------+
     |getpwent()  | Thread safety | MT-Unsafe race:pwent        |
     |            |               | race:pwentbuf locale        |
     +------------+---------------+-----------------------------+
     |setpwent(), | Thread safety | MT-Unsafe race:pwent locale |
     |endpwent()  |               |                             |
     +------------+---------------+-----------------------------+
     In  the  above  table, pwent in race:pwent signifies that if any of the
     functions setpwent(), getpwent(), or endpwent() are used in parallel in
     different threads of a program, then data races could occur.

CONFORMING TO

     POSIX.1-2001,  POSIX.1-2008,  SVr4,  4.3BSD.  The pw_gecos field is not
     specified in POSIX, but is present on most implementations.

SEE ALSO

     fgetpwent(3), getpw(3), getpwent_r(3), getpwnam(3), getpwuid(3),  putp-
     went(3), passwd(5)

COLOPHON

     This  page  is  part of release 4.16 of the Linux man-pages project.  A
     description of the project, information about reporting bugs,  and  the
     latest     version     of     this    page,    can    be    found    at
     https://www.kernel.org/doc/man-pages/.

GNU 2017-09-15 GETPWENT(3)

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