Shell Programming and Scripting

Friends,
I observed a peculiar problem in shell.

if I set a variable using standard input and backspace was used by the user, then the variable get ^? characters embedded in the variable.

###
echo "Enter value for X="
read X
echo $X
expr $X + 1
###
If the variable is echoed, then there is no problem but if I try to perform any mathematical operation say addition then it displays an error like "123^?^?^?23" integer expected.
How can I supress these symbols so that the expr command does not fail.


Please help...

Backspace ought to work there, but your terminal and your server don't agree on what character a backspace is. ^? is an ASCII 127, meaning 'DEL', your terminal is probably expecting an ASCII 8, or 'BS'.

It'd be much better to fix the backspace than to filter out ^?. What's your system? What's your shell? What's your terminal software?

Ideally you could alter your terminal to send the appropriate character instead of ASCII 127's for backspace.

But you can try running stty erase ^? which should tell your program to use ASCII 127's as backspace characters. It seems like your system has done stty erase ^H so expects BS instead -- when I do that myself, I get the same behavior, ^? popping up instead of backspace functioning...

Thanks

stty erase ^? solved the problem.