247 lines
4.7 KiB
HTML
247 lines
4.7 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of GETPASS</TITLE>
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</HEAD><BODY>
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<H1>GETPASS</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2019-03-06<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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getpass - get a password
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>#include <<A HREF="file:///usr/include/unistd.h">unistd.h</A>></B>
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<P>
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<B>char *getpass(const char *</B><I>prompt</I><B>);</B>
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<P>
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Feature Test Macro Requirements for glibc (see
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<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
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<P>
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<B>getpass</B>():
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<DL COMPACT><DT id="1"><DD>
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<DL COMPACT>
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<DT id="2">Since glibc 2.2.2:<DD>
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<PRE>
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_XOPEN_SOURCE && ! (_POSIX_C_SOURCE >= 200112L)
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|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
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|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
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</PRE>
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<DT id="3">Before glibc 2.2.2:<DD>
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none
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</DL>
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</DL>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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This function is obsolete.
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Do not use it.
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If you want to read input without terminal echoing enabled,
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see the description of the
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<I>ECHO</I>
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flag in
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<B><A HREF="/cgi-bin/man/man2html?3+termios">termios</A></B>(3).
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<P>
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The
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<B>getpass</B>()
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function opens
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<I>/dev/tty</I>
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(the controlling terminal of the process), outputs the string
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<I>prompt</I>,
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turns off echoing, reads one line (the "password"),
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restores the terminal state and closes
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<I>/dev/tty</I>
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again.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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The function
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<B>getpass</B>()
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returns a pointer to a static buffer containing (the first
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<B>PASS_MAX</B>
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bytes of) the password without the trailing
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newline, terminated by a null byte ('\0').
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This buffer may be overwritten by a following call.
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On error, the terminal state is restored,
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<I>errno</I>
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is set appropriately, and NULL is returned.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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The function may fail if
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<DL COMPACT>
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<DT id="4"><B>ENXIO</B>
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<DD>
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The process does not have a controlling terminal.
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</DL>
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<A NAME="lbAG"> </A>
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<H2>FILES</H2>
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<I>/dev/tty</I>
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<A NAME="lbAH"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>getpass</B>()
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</TD><TD>Thread safety</TD><TD>MT-Unsafe term<BR></TD></TR>
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</TABLE>
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<A NAME="lbAI"> </A>
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<H2>CONFORMING TO</H2>
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Present in SUSv2, but marked LEGACY.
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Removed in POSIX.1-2001.
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<A NAME="lbAJ"> </A>
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<H2>NOTES</H2>
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<P>
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In the GNU C library implementation, if
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<I>/dev/tty</I>
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cannot be opened, the prompt is written to
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<I>stderr</I>
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and the password is read from
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<I>stdin</I>.
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There is no limit on the length of the password.
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Line editing is not disabled.
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<P>
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According to SUSv2, the value of
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<B>PASS_MAX</B>
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must be defined in
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<I><<A HREF="file:///usr/include/limits.h">limits.h</A>></I>
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in case it is smaller than 8, and can in any case be obtained using
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<I>sysconf(_SC_PASS_MAX)</I>.
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However, POSIX.2 withdraws the constants
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<B>PASS_MAX</B>
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and
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<B>_SC_PASS_MAX</B>,
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and the function
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<B>getpass</B>().
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The glibc version accepts
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<B>_SC_PASS_MAX</B>
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and returns
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<B>BUFSIZ</B>
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(e.g., 8192).
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<A NAME="lbAK"> </A>
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<H2>BUGS</H2>
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The calling process should zero the password as soon as possible to avoid
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leaving the cleartext password visible in the process's address space.
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<A NAME="lbAL"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+crypt">crypt</A></B>(3)
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<A NAME="lbAM"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="5"><A HREF="#lbAB">NAME</A><DD>
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<DT id="6"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="7"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="8"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="9"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="10"><A HREF="#lbAG">FILES</A><DD>
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<DT id="11"><A HREF="#lbAH">ATTRIBUTES</A><DD>
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<DT id="12"><A HREF="#lbAI">CONFORMING TO</A><DD>
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<DT id="13"><A HREF="#lbAJ">NOTES</A><DD>
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<DT id="14"><A HREF="#lbAK">BUGS</A><DD>
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<DT id="15"><A HREF="#lbAL">SEE ALSO</A><DD>
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<DT id="16"><A HREF="#lbAM">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:44 GMT, March 31, 2021
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</BODY>
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</HTML>
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