What does `echo ${!a}` do and why?
38607
Variable substitution with an exclamation mark in bash
120214
What's the difference between <<, <<< and < < in bash?
124298
What is the right way to use the `\!` spacing command?
71607
What's this =! operator?
42368
Why does the exclamation mark `!` sometimes upset bash?
7431
How does ${!#} work in bash to get the last command-line argument?
126498
What is the purpose of the : (colon) GNU Bash builtin?
54313
What is $() in a command?
158457
Using | pipe character from a $variable makes it treat as just another argument in bash; how to escape it?
27742
What does "${-#*i}" != "$-" mean?
3574
What is the !! (not not) operator in JavaScript?
83409
Difference between $ and # in Linux environment
126174
What is the difference between != and  operators?
138524
$* in bash scripting
120900
${!FOO} and zsh
20348
What does the '!' really do when it's added to an ex command (:wq! | :w! | :q! )?
154604
Why is there a /bin/echo and why would I want to use it?