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       This  function  is obsolete.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 terminal 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 corresponding characters (usually control-C,  control-\,  control-Z
       and control-Y) are transmitted 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 3.54 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/.