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[dragonfly.git] / lib / libc / gen / getpass.3
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1.\" Copyright (c) 1989, 1991, 1993
2.\" The Regents of the University of California. All rights reserved.
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32.\" @(#)getpass.3 8.1 (Berkeley) 6/4/93
33.\" $FreeBSD: src/lib/libc/gen/getpass.3,v 1.6.2.4 2002/06/30 14:01:45 des Exp $
1de703da 34.\" $DragonFly: src/lib/libc/gen/getpass.3,v 1.2 2003/06/17 04:26:42 dillon Exp $
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35.\"
36.Dd June 4, 1993
37.Dt GETPASS 3
38.Os
39.Sh NAME
40.Nm getpass
41.Nd get a password
42.Sh LIBRARY
43.Lb libc
44.Sh SYNOPSIS
45.In pwd.h
46.In unistd.h
47.Ft char *
48.Fn getpass "const char *prompt"
49.Sh DESCRIPTION
50The
51.Fn getpass
52function displays a prompt to, and reads in a password from,
53.Pa /dev/tty .
54If this file is not accessible,
55.Fn getpass
56displays the prompt on the standard error output and reads from the standard
57input.
58.Pp
59The password may be up to _PASSWORD_LEN (currently 128)
60characters in length.
61Any additional
62characters and the terminating newline character are discarded.
63.Pp
64The
65.Fn getpass
66function turns off character echoing while reading the password.
67.Sh RETURN VALUES
68The
69.Fn getpass
70function returns a pointer to the null terminated password.
71.Sh FILES
72.Bl -tag -width /dev/tty -compact
73.It Pa /dev/tty
74.El
75.Sh SEE ALSO
76.Xr crypt 3 ,
77.Xr readpassphrase 3
78.Sh HISTORY
79A
80.Fn getpass
81function appeared in
82.At v7 .
83.Sh BUGS
84The
85.Fn getpass
86function leaves its result in an internal static object and returns
87a pointer to that object.
88Subsequent calls to
89.Fn getpass
90will modify the same object.
91.Pp
92The calling process should zero the password as soon as possible to
93avoid leaving the cleartext password visible in the process's address
94space.
95.Pp
96Upon receipt of a SIGTSTP, the input buffer will be flushed, so any
97partially typed password must be retyped when the process
98continues.