Filter away non-printable ASCII characters on Linux?

Sometimes the commands’ output have some non-printable ASCII characters. How to filter away these non-printable ASCII characters on Linux? You can consider the problem as “how to leave only printable ascii characters?”. The printable characters in ASCII table are: Octal 011: Tab Octal 012: Line Feed Octal 015: Carriage Return Octal 040 to 176: printable […]

Bash comparison operators

What are all the bash supported comparison operators? The man 1 test contains all the operators supported in bash. An omitted EXPRESSION defaults to false. Otherwise, EXPRESSION is true or false and sets exit status. It is one of: ( EXPRESSION ) EXPRESSION is true ! EXPRESSION EXPRESSION is false EXPRESSION1 -a EXPRESSION2 both EXPRESSION1 […]

Alternatives to goto in bash

As we know: There is no goto statement support in bash. goto is useful for certain situations, especially for debugging. So, is there any alternative mechanisms to goto in bash? Robert Copeland gave an interesting hacking to this problem: http://bobcopeland.com/blog/2012/10/goto-in-bash/ The idea is like the self-modifying code. But the difference is to generate a piece […]