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\"     @(#)getpwent.3   8.2 (Berkeley) 12/11/93
\"
Dd February 7, 2018
Dt GETPWENT 3
Os
Sh NAME
Nm getpwent ,
Nm getpwent_r ,
Nm getpwnam ,
Nm getpwnam_r ,
Nm getpwuid ,
Nm getpwuid_r ,
Nm setpassent ,
Nm setpwent ,
Nm endpwent
Nd password database operations
Sh LIBRARY
Lb libc
Sh SYNOPSIS
In pwd.h
Ft struct passwd *
Fn getpwent void
Ft int
Fo getpwent_r
Fa "struct passwd *pw"
Fa "char *buffer"
Fa "size_t buflen"
Fa "struct passwd **result"
Fc
Ft struct passwd *
Fn getpwnam "const char *name"
Ft int
Fo getpwnam_r
Fa "const char *name"
Fa "struct passwd *pw"
Fa "char *buffer"
Fa "size_t buflen"
Fa "struct passwd **result"
Fc
Ft struct passwd *
Fn getpwuid "uid_t uid"
Ft int
Fo getpwuid_r
Fa "uid_t uid"
Fa "struct passwd *pw"
Fa "char *buffer"
Fa "size_t buflen"
Fa "struct passwd **result"
Fc
Ft int
Fn setpassent "int stayopen"
Ft void
Fn setpwent void
Ft void
Fn endpwent void
Sh DESCRIPTION
These functions
operate on the password database
which is described
in
Xr passwd 5 .
Each entry in the database is defined by the structure
Ar passwd
found in the include
file
In pwd.h :
Bd -literal -offset indent
struct passwd {
       char    *pw_name;       /* user name */
       char    *pw_passwd;     /* encrypted password */
       uid_t   pw_uid;         /* user uid */
       gid_t   pw_gid;         /* user gid */
       time_t  pw_change;      /* password change time */
       char    *pw_class;      /* user login class */
       char    *pw_gecos;      /* general information */
       char    *pw_dir;        /* home directory */
       char    *pw_shell;      /* default shell */
       time_t  pw_expire;      /* account expiration */
};
Ed
Pp
The functions
Fn getpwnam
and
Fn getpwuid
search the password database for the given user name pointed to by
Ar name
or user id pointed to by
Ar uid
respectively, always returning the first one encountered.
Identical user names or user ids may result in undefined behavior.
Pp
The
Fn getpwent
function
sequentially reads the password database and is intended for programs
that wish to process the complete list of users.
Pp
The functions
Fn getpwnam_r ,
Fn getpwuid_r ,
and
Fn getpwent_r
act like their non re-entrant counterparts, updating the contents of
Ar pw
and storing a pointer to that in
Ar result ,
and returning
Dv 0 .
Storage used by
Ar pw
is allocated from
Ar buffer ,
which is
Ar buflen
bytes in size.
If the requested entry cannot be found,
Ar result
will point to
Dv NULL
and
Dv 0
will be returned.
If an error occurs,
a non-zero error number will be returned and
Ar result
will point to
Dv NULL .
Calling
Fn getpwent_r
from multiple threads will result in each thread reading a disjoint portion
of the password database.
Pp
The
Fn setpassent
function
accomplishes two purposes.
First, it causes
Fn getpwent
to
Dq rewind
to the beginning of the database.
Additionally, if
Fa stayopen
is non-zero, file descriptors are left open, significantly speeding
up subsequent accesses for all of the functions.
(This latter functionality is unnecessary for
Fn getpwent
as it doesn't close its file descriptors by default.)
Pp
It is dangerous for long-running programs to keep the file descriptors
open as the database will become out of date if it is updated while the
program is running.
Pp
The
Fn setpwent
function
is equivalent to
Fn setpassent
with an argument of zero.
Pp
The
Fn endpwent
function
closes any open files.
Pp
These functions have been written to
Dq shadow
the password file, e.g. allow only certain programs to have access
to the encrypted password.
If the process which calls them has an effective uid of 0, the encrypted
password will be returned, otherwise, the password field of the returned
structure will point to the string
Ql * .
Sh RETURN VALUES
The functions
Fn getpwent ,
Fn getpwnam ,
and
Fn getpwuid ,
return a valid pointer to a passwd structure on success
and a
Dv NULL
pointer if the entry was not found or an error occurred.
If an error occurred, the global variable
Dv errno
is set to indicate the nature of the failure.
The
Fn setpassent
function returns 0 on failure, setting the global variable
Dv errno
to indicate the nature of the failure, and 1 on success.
The
Fn endpwent
and
Fn setpwent
functions
have no return value.
The functions
Fn getpwnam_r ,
Fn getpwuid_r ,
and
Fn getpwent_r
return
Dv 0
on success or entry not found, and non-zero on failure, setting the global
variable
Dv errno
to indicate the nature of the failure.
Sh FILES
Bl -tag -width /etc/master.passwd -compact
It Pa /etc/pwd.db
The insecure password database file
It Pa /etc/spwd.db
The secure password database file
It Pa /etc/master.passwd
The current password file
It Pa /etc/passwd
A Version 7 format password file
El
Sh COMPATIBILITY
The historic function
Fn setpwfile
which allowed the specification of alternative password databases,
has been deprecated and is no longer available.
Sh ERRORS
The following error codes may be set in
Va errno
for
Nm getpwent ,
Nm getpwent_r ,
Nm getpwnam ,
Nm getpwnam_r ,
Nm getpwuid ,
Nm getpwuid_r ,
and
Nm setpassent :
Bl -tag -width Er
It Bq Er EINTR
A signal was caught during the database search.
It Bq Er EIO
An I/O error has occurred.
It Bq Er EMFILE
The limit on open files for this process has been reached.
It Bq Er ENFILE
The system limit on open files has been reached.
El
Pp
The following error code may be set in
Va errno
for
Nm getpwent_r ,
Nm getpwnam_r ,
and
Nm getpwuid_r :
Bl -tag -width Er
It Bq Er ERANGE
The resulting
Ft struct passwd
does not fit in the space defined by
Dv buffer
and
Dv buflen .
El
Pp
Other
Dv errno
values may be set depending on the specific database backends.
Sh SEE ALSO
Xr getlogin 2 ,
Xr getgrent 3 ,
Xr nsswitch.conf 5 ,
Xr passwd 5 ,
Xr passwd.conf 5 ,
Xr pwd_mkdb 8 ,
Xr vipw 8
Sh STANDARDS
The
Fn getpwnam
and
Fn getpwuid ,
functions conform to
St -p1003.1-90 .
The
Fn getpwnam_r
and
Fn getpwuid_r
functions conform to
St -p1003.1c-95 .
The
Fn endpwent ,
Fn getpwent ,
and
Fn setpwent
functions conform to
St -xpg4.2
and
St -p1003.1-2004
(XSI extension).
Sh HISTORY
The
Nm getpwent ,
Nm getpwnam ,
Nm getpwuid ,
Nm setpwent ,
and
Nm endpwent
functions appeared in
At v7 .
The
Nm setpassent
function appeared in
Bx 4.3 Reno .
The functions
Fn getpwnam_r
and
Fn getpwuid_r
appeared in
Nx 3.0 .
Sh BUGS
The functions
Fn getpwent ,
Fn getpwnam ,
and
Fn getpwuid ,
leave their results in an internal static object and return
a pointer to that object.
Subsequent calls to any of these functions will modify the same object.
Pp
The functions
Fn getpwent ,
Fn endpwent ,
Fn setpassent ,
and
Fn setpwent
are fairly useless in a networked environment and should be
avoided, if possible.
Fn getpwent
makes no attempt to suppress duplicate information if multiple
sources are specified in
Xr nsswitch.conf 5 .

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