Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
Echoes the name of the current user's terminal. Note that each separate xterm window counts as a
different terminal.
stty
bash$ tty
/dev/pts/1
Shows and/or changes terminal settings. This complex command, used in a script, can control
terminal behavior and the way output displays. See the info page, and study it carefully.
Example 13−1. setting an erase character
#!/bin/bash
# erase.sh: Using "stty" to set an erase character when reading input.
echo −n "What is your name? "
read name
echo "Your name is $name."
stty erase '#'
echo −n "What is your name? "
read name
echo "Your name is $name."
# Try to erase characters of input.
# Won't work.
# Set "hashmark" (#) as erase character.
# Use # to erase last character typed.
exit 0
Example 13−2. secret password: Turning off terminal echoing
#!/bin/bash
echo
echo −n "Enter password "
read passwd
echo "password is $passwd"
echo −n "If someone had been looking over your shoulder, "
echo "your password would have been compromised."
echo && echo # Two line−feeds in an "and list".
stty −echo
# Turns off screen echo.
echo −n "Enter password again "
read passwd
echo
echo "password is $passwd"
echo
stty echo
# Restores screen echo.
exit 0
A creative use of stty is detecting a user keypress (without hitting ENTER).
Example 13−3. Keypress detection
Chapter 13. System and Administrative Commands 217