lists a few of the supported operators..
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This table lists some of the common backslash escape sequences. The idea behind using the backslash originated in the C programming language and has been adopted by many others, including the shell.
Adding the -e option to echo will enable interpretation of escape sequences. You may also place them inside $' '. Here, using the sleep command, a simple program that just waits for the specified number of seconds and then exits, we can create a primitive countdown timer.
sleep 10; echo -e "Time's up\a"
We could also do this:
sleep 10; echo "Time's up" $'\a'
As we move forward with using the shell, we will find that expansions and quoting will be used with increasing frequency, so it makes sense to get a good understanding of the way they work. In fact, it could be argued that they are the most important subjects to learn about the shell. Without a proper understanding of expansion, the shell will always be a source of mystery and confusion, and much of its potential power will be wasted.
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