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GETPASS(3)			    Linux Programmer's Manual			       GETPASS(3)

NAME
       getpass - get a password

SYNOPSIS
       #include <unistd.h>

       char *getpass( const char *prompt);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getpass():
	   Since glibc 2.2.2:
	       _BSD_SOURCE ||
		   (_XOPEN_SOURCE >= 500 ||
		       _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
		   !(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
	   Before glibc 2.2.2:
	       none

DESCRIPTION
       This  function  is  obsolete.   Do not use it.  If you want to read input without terminal
       echoing enabled, see the description of the ECHO flag in termios(3).

       The getpass() function opens /dev/tty (the controlling terminal of the  process),  outputs
       the string prompt, turns off echoing, reads one line (the "password"), restores the termi-
       nal state and closes /dev/tty again.

RETURN VALUE
       The function getpass() returns a pointer to a static buffer containing (the first PASS_MAX
       bytes  of)  the	password  without the trailing newline, terminated by a null byte ('\0').
       This buffer may be overwritten by a following call.   On  error,  the  terminal	state  is
       restored, errno is set appropriately, and NULL is returned.

ERRORS
       The function may fail if

       ENXIO  The process does not have a controlling terminal.

FILES
       /dev/tty

ATTRIBUTES
   Multithreading (see pthreads(7))
       The getpass() function is not thread-safe.

CONFORMING TO
       Present in SUSv2, but marked LEGACY.  Removed in POSIX.1-2001.

NOTES
       For  libc4  and	libc5, the prompt is not written to /dev/tty but to stderr.  Moreover, if
       /dev/tty cannot be opened, the password is read from stdin.  The static buffer has  length
       128  so	that  only  the  first 127 bytes of the password are returned.	While reading the
       password, signal generation (SIGINT, SIGQUIT, SIGSTOP, SIGTSTP) is disabled and the corre-
       sponding  characters (usually control-C, control-\, control-Z and control-Y) are transmit-
       ted as part of the password.  Since libc 5.4.19 also line editing  is  disabled,  so  that
       also backspace and the like will be seen as part of the password.

       For glibc2, if /dev/tty cannot be opened, the prompt is written to stderr and the password
       is read from stdin.  There is no limit on the length of the password.  Line editing is not
       disabled.

       According  to the SUSv2, the value of PASS_MAX must be defined in <limits.h> in case it is
       smaller than 8, and can in any case be  obtained  using	sysconf(_SC_PASS_MAX).	 However,
       POSIX.2	withdraws  the	constants  PASS_MAX and _SC_PASS_MAX, and the function getpass().
       Libc4  and  libc5  have	never  supported  PASS_MAX  or	_SC_PASS_MAX.	 Glibc2   accepts
       _SC_PASS_MAX and returns BUFSIZ (e.g., 8192).

BUGS
       The  calling  process  should  zero  the password as soon as possible to avoid leaving the
       cleartext password visible in the process's address space.

SEE ALSO
       crypt(3)

COLOPHON
       This page is part of release 3.55 of the Linux man-pages project.  A  description  of  the
       project,     and    information	  about    reporting	bugs,	 can	be    found    at
       http://www.kernel.org/doc/man-pages/.

Linux					    2013-06-21				       GETPASS(3)
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