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

       getpass - get a password

       #include <unistd.h>

       char *getpass( const char *prompt);

       This function is obsolete.  Do not use it.

       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.

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

       The function may fail if

       ENXIO  The process does not have a controlling terminal.


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

       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,  SIGTSTOP)
       is disabled and the corresponding characters (usually control-C, control-\, control-Z and control-Y) are trans-
       mitted 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).

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


       This page is part of release 3.22 of the Linux man-pages project.  A description of the project,  and  informa-
       tion about reporting bugs, can be found at

Linux                             2000-12-05                        GETPASS(3)