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'\" et
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.TH ENDPWENT "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.SH PROLOG
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This manual page is part of the POSIX Programmer's Manual.
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The Linux implementation of this interface may differ (consult
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the corresponding Linux manual page for details of Linux behavior),
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or the interface may not be implemented on Linux.
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.SH NAME
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endpwent,
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getpwent,
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setpwent
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\(em user database functions
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.SH SYNOPSIS
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.LP
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.nf
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#include <pwd.h>
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.P
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void endpwent(void);
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struct passwd *getpwent(void);
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void setpwent(void);
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.fi
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.SH DESCRIPTION
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These functions shall retrieve information about users.
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.P
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The
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\fIgetpwent\fR()
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function shall return a pointer to a structure containing the broken-out
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fields of an entry in the user database. Each entry in the user
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database contains a
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.BR passwd
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structure. When first called,
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\fIgetpwent\fR()
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shall return a pointer to a
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.BR passwd
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structure containing the first entry in the user database. Thereafter,
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it shall return a pointer to a
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.BR passwd
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structure containing the next entry in the user database. Successive
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calls can be used to search the entire user database.
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.P
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If an end-of-file or an error is encountered on reading,
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\fIgetpwent\fR()
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shall return a null pointer.
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.P
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An implementation that provides extended security controls may impose
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further implementation-defined restrictions on accessing the user
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database. In particular, the system may deny the existence of some or
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all of the user database entries associated with users other than the
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caller.
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.P
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The
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\fIsetpwent\fR()
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function effectively rewinds the user database to allow repeated
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searches.
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.P
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The
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\fIendpwent\fR()
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function may be called to close the user database when processing is
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complete.
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.P
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These functions need not be thread-safe.
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.SH "RETURN VALUE"
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The
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\fIgetpwent\fR()
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function shall return a null pointer on end-of-file or error.
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.P
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The application shall not modify the structure to which the return
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value points, nor any storage areas pointed to by pointers within the
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structure. The returned pointer, and pointers within the structure,
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might be invalidated or the structure or the storage areas might be
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overwritten by a subsequent call to
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\fIgetpwuid\fR(),
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\fIgetpwnam\fR(),
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or
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\fIgetpwent\fR().
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.SH ERRORS
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These functions may fail if:
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.TP
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.BR EIO
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An I/O error has occurred.
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.P
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In addition,
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\fIgetpwent\fR()
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and
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\fIsetpwent\fR()
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may fail if:
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.TP
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.BR EMFILE
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All file descriptors available to the process are currently open.
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.TP
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.BR ENFILE
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The maximum allowable number of files is currently open in the system.
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.LP
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.IR "The following sections are informative."
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.SH EXAMPLES
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.SS "Searching the User Database"
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.P
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The following example uses the
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\fIgetpwent\fR()
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function to get successive entries in the user database, returning a
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pointer to a
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.BR passwd
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structure that contains information about each user. The call to
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\fIendpwent\fR()
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closes the user database and cleans up.
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.sp
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.RS 4
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.nf
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\fB
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#include <pwd.h>
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#include <stdio.h>
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.P
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void printname(uid_t uid)
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{
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struct passwd *pwd;
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.P
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setpwent();
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while((pwd = getpwent()) != NULL) {
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if (pwd->pw_uid == uid) {
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printf("name=%s\en",pwd->pw_name);
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break;
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}
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}
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endpwent();
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}
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.fi \fR
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.P
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.RE
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.SH "APPLICATION USAGE"
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These functions are provided due to their historical usage.
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Applications should avoid dependencies on fields in the password
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database, whether the database is a single file, or where in the
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file system name space the database resides. Applications should use
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\fIgetpwuid\fR()
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whenever possible because it avoids these dependencies.
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.SH RATIONALE
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None.
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.SH "FUTURE DIRECTIONS"
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None.
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.SH "SEE ALSO"
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.IR "\fIendgrent\fR\^(\|)",
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.IR "\fIgetlogin\fR\^(\|)",
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.IR "\fIgetpwnam\fR\^(\|)",
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.IR "\fIgetpwuid\fR\^(\|)"
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.P
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The Base Definitions volume of POSIX.1\(hy2008,
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.IR "\fB<pwd.h>\fP"
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 7, Copyright (C) 2013 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group.
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(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
|
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is the referee document. The original Standard can be obtained online at
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http://www.unix.org/online.html .
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Any typographical or formatting errors that appear
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in this page are most likely
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to have been introduced during the conversion of the source files to
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man page format. To report such errors, see
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https://www.kernel.org/doc/man-pages/reporting_bugs.html .
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