mirror of https://github.com/mkerrisk/man-pages
201 lines
4.9 KiB
Groff
201 lines
4.9 KiB
Groff
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\"
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.\" Modified Sat Jul 24 19:22:14 1993 by Rik Faith (faith@cs.unc.edu)
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.\" Modified Mon May 27 21:37:47 1996 by Martin Schulze (joey@linux.de)
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.\"
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.TH GETPWENT 3 2017-09-15 "GNU" "Linux Programmer's Manual"
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.SH NAME
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getpwent, setpwent, endpwent \- get password file entry
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.SH SYNOPSIS
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.nf
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.B #include <sys/types.h>
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.B #include <pwd.h>
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.PP
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.B struct passwd *getpwent(void);
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.PP
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.B void setpwent(void);
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.PP
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.B void endpwent(void);
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.fi
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.PP
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.RS -4
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.RE
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.PP
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.ad l
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.BR getpwent (),
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.BR setpwent (),
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.BR endpwent ():
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.RS 4
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_XOPEN_SOURCE\ >=\ 500
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.\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
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|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
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|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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.RE
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.ad b
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.SH DESCRIPTION
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The
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.BR getpwent ()
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function returns a pointer to a structure containing
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the broken-out fields of a record from the password database
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(e.g., the local password file
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.IR /etc/passwd ,
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NIS, and LDAP).
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The first time
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.BR getpwent ()
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is called, it returns the first entry; thereafter, it returns successive
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entries.
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.PP
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The
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.BR setpwent ()
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function rewinds to the beginning
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of the password database.
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.PP
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The
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.BR endpwent ()
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function is used to close the password database
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after all processing has been performed.
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.PP
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The \fIpasswd\fP structure is defined in \fI<pwd.h>\fP as follows:
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.PP
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.in +4n
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.EX
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struct passwd {
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char *pw_name; /* username */
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char *pw_passwd; /* user password */
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uid_t pw_uid; /* user ID */
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gid_t pw_gid; /* group ID */
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char *pw_gecos; /* user information */
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char *pw_dir; /* home directory */
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char *pw_shell; /* shell program */
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};
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.EE
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.in
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.PP
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For more information about the fields of this structure, see
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.BR passwd (5).
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.SH RETURN VALUE
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The
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.BR getpwent ()
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function returns a pointer to a
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.I passwd
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structure, or NULL if
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there are no more entries or an error occurred.
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If an error occurs,
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.I errno
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is set appropriately.
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If one wants to check
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.I errno
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after the call, it should be set to zero before the call.
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.PP
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The return value may point to a static area, and may be overwritten
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by subsequent calls to
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.BR getpwent (),
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.BR getpwnam (3),
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or
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.BR getpwuid (3).
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(Do not pass the returned pointer to
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.BR free (3).)
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.SH ERRORS
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.TP
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.B EINTR
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A signal was caught; see
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.BR signal (7).
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.TP
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.B EIO
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I/O error.
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.TP
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.B EMFILE
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The per-process limit on the number of open file descriptors has been reached.
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.TP
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.B ENFILE
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The system-wide limit on the total number of open files has been reached.
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.TP
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.B ENOMEM
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.\" not in POSIX
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Insufficient memory to allocate
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.I passwd
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structure.
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.\" to allocate the passwd structure, or to allocate buffers
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.TP
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.B ERANGE
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Insufficient buffer space supplied.
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.SH FILES
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.TP
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.I /etc/passwd
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local password database file
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.TS
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allbox;
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lbw11 lb lb
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l l l.
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Interface Attribute Value
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T{
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.BR getpwent ()
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T} Thread safety T{
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MT-Unsafe race:pwent
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.br
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race:pwentbuf locale
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T}
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T{
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.BR setpwent (),
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.br
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.BR endpwent ()
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T} Thread safety MT-Unsafe race:pwent locale
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.TE
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.sp 1
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In the above table,
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.I pwent
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in
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.I race:pwent
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signifies that if any of the functions
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.BR setpwent (),
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.BR getpwent (),
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or
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.BR endpwent ()
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are used in parallel in different threads of a program,
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then data races could occur.
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.SH CONFORMING TO
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POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
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The
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.I pw_gecos
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field is not specified in POSIX, but is present on most implementations.
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.SH SEE ALSO
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.BR fgetpwent (3),
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.BR getpw (3),
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.BR getpwent_r (3),
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.BR getpwnam (3),
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.BR getpwuid (3),
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.BR putpwent (3),
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.BR passwd (5)
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