?
Solved

How to hide the typed characters

Posted on 2001-09-03
9
Medium Priority
?
201 Views
Last Modified: 2013-12-03
I want to accept the password,so don't want to display the characters.How do I hide this ,I am using C ang Gcc to compile.
Using getch() gives a peculiar error.Says two other library functions are undefined.
Help.
0
Comment
Question by:rasaraja
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 2
  • 2
  • +2
9 Comments
 
LVL 5

Expert Comment

by:garboua
ID: 6453629
why don't you use pam?
0
 
LVL 51

Expert Comment

by:ahoffmann
ID: 6456131
see ioctl()
0
 

Author Comment

by:rasaraja
ID: 6459249
Would you kindly be a bit more descriptive?What's pam ?
0
 [eBook] Windows Nano Server

Download this FREE eBook and learn all you need to get started with Windows Nano Server, including deployment options, remote management
and troubleshooting tips and tricks

 
LVL 5

Expert Comment

by:bryanh
ID: 6468955
I assume you're reading the password from a regular tty (terminal; virtual console; X pseudo-tty; whatever).  What causes what you type to display on the terminal is the tty line discipline (basically, a device driver) in the kernel.  You can change this default setting with a command 'stty -echo" (and view the current settings with 'stty -a').  Do a 'man stty' and play around with it.

Stty turns echoing on and off by issuing a TCSETATTR ioctl, via the tcsetattr() library function.  Man tcsetattr (or better, read the GNU C library user's guide) for details.  Your program can turn echoing off with a tcsetattr(), read the password, then turn echoing back on.

As for why getch() doesn't work for you, that's another question and you need to provide more details.  It works for me.

I know little about pam -- I have found it only to be a pain in the butt.  However, it provides library functions that handle the turning off of echoing and many other things.  If it's not too complicated for what you're doing, it might be the right way to go and garboua can give you more information.




0
 

Author Comment

by:rasaraja
ID: 6469299
HI bryanh,

It would be great if u can tell me how I can use getch.I am ready tp provide all the details you require.
0
 
LVL 5

Expert Comment

by:bryanh
ID: 6471233
What library does the compiler (or whatever) complain about being undefined?  Could you post the exact error messages?
0
 

Accepted Solution

by:
acarna earned 200 total points
ID: 6478212
Hi!
Also you could use the getpass() function:

#include <stdlib.h>

char *getpass(const char *prompt);


Note that "getpass" truncates the typed password to at most eight characters.


Regards.

Ariel.
0
 

Author Comment

by:rasaraja
ID: 6481258
Acarna,this is exactly what I was looking for.But it does not seem that getpass() truncates to 8 chars.
0
 

Expert Comment

by:acarna
ID: 6481440
Oh, yes! If you are using a modern Unix maybe the function don't truncate the string but the primitive and old getpass(), you can be sure truncate the data.
Have this in mind in matters as portability.

Regards.
0

Featured Post

Enroll in August's Course of the Month

August's CompTIA IT Fundamentals course includes 19 hours of basic computer principle modules and prepares you for the certification exam. It's free for Premium Members, Team Accounts, and Qualified Experts!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Have you ever been frustrated by having to click seven times in order to retrieve a small bit of information from the web, always the same seven clicks, scrolling down and down until you reach your target? When you know the benefits of the command l…
The purpose of this article is to fix the unknown display problem in Linux Mint operating system. After installing the OS if you see Display monitor is not recognized then we can install "MESA" utilities to fix this problem or we can install additio…
Excel styles will make formatting consistent and let you apply and change formatting faster. In this tutorial, you'll learn how to use Excel's built-in styles, how to modify styles, and how to create your own. You'll also learn how to use your custo…
If you’ve ever visited a web page and noticed a cool font that you really liked the look of, but couldn’t figure out which font it was so that you could use it for your own work, then this video is for you! In this Micro Tutorial, you'll learn yo…
Suggested Courses
Course of the Month12 days, 7 hours left to enroll

777 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question