making a .sh wait for user input Post: 46665

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Top Forums UNIX for Dummies Questions & Answers making a .sh wait for user input Post 46665 by Perderabo on Wednesday 21st of January 2004 09:19:44 PM

01-21-2004

Administrator Emeritus

Don't apologize. There is nothing wrong with posting a followup to an old thread. The only problem is it would take a book to really answer your question. I'll take a shot at a summary.

The tty driver controls how input lines that you type are delivered to programs. Normally a tty driver will wait until a complete line is available. It also handles stuff like backspace so that program doesn'y need to. The stty command lets you change the way the tty driver works. "stty -a" will display all of the settings. You should do that to see what's available.

"stty -g" displays all of the settings too. But it's encoded and you can't understand the output. But you can save the output and feed it back into the stty command. So:
oldtty=`stty -g`
stty $oldstty
will save and restore the original settings of the tty driver.

stty -canon -echo min 1 time 0
is setting some options in the tty driver. -icanon turns off all special character processing. Now a backspace will be passed to the program rather than being processed. And a carriage return won't terminate a line. So now min and time control when a read has finished. "min 1" says we need at least one character. "time 0" means that we won't wait a while before completing a read. So each read from the program may return after just one character.

the -echo just turns off echo. I would not have done that.

dd is a program that is prepared to read data that is not organized into lines. This dd will read one block (count=1) of data. And that block will be one character in length (size=1). So the dd will read one character and return to the script.

The final echo moves the cursor to the next line.

Perderabo

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LEARN ABOUT DEBIAN

falselogin

FALSELOGIN(1)						      General Commands Manual						     FALSELOGIN(1)

NAME

       falselogin - a false login shell

SYNOPSIS

       /usr/bin/falselogin

DESCRIPTION

       falselogin is a small application which can deny the user to log in the system displaying a custom message.

CONFIGURATION

       The configuration file for falselogin is /etc/falselogin.conf. Everything you write into this file will be written at login except for some
       special strings which will be substituted when they appear in the configuration file. They are:

       %mail% string
	      Number of mail messages in the user's mailbox.

       %user% string
	      Username.

       %sysname% string
	      Sysname from uname. (eg: Linux)

       %nodename%, %host% strings
	      The hostname. (eg: master)

       %release% string
	      Linux kernel version number (eg: 2.0.36)

       %version% string
	      Linux version number (eg: #8 Sun Dec 20 12:02:31 CET 1998)

       %machine% string
	      Machine type (eg: i686)

       %debian_version% string
	      Debian version from /etc/debian_version

PARAMETERS

       --wait, -w waitfor
	      If waitfor is a number, falselogin will sleep waitfor seconds before exiting; if waitfor matches the word  'enter'  then	falselogin
	      will wait for the user to input the 'enter' key

AUTHOR

       This manual page was written by Tibor Koleszar <t.koleszar@somogy.hu>, for the Debian GNU/Linux system.

																     FALSELOGIN(1)