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Asked: 2011-04-18 00:37:07 +0800 CST

How to interpret this command chaining?

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[root@localhost /]# ( ./address_to_char;cat) | ./overflow

How does ( ./address_to_char;cat) work here?

What's different from ./address_to_char|./overflow?

bash

2 Answers

  1. Well the parentheses open a sub shell and the semi colon will run the commands sequentially.

    So in this case, you are running ./address_to_char then cat in a subshell.

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  2. Best Answer

    The outputs of both ./address_to_char and cat are piped to ./overflow as a single, continuous stream of data.

    1. First, ./address_to_char is run, and its output is redirected to ./overflow's input.

    2. When ./address_to_char exits, cat is started, and its output is attached to the still-running ./overflow process in the same way.

      Since cat was run with no files specified, it reads from stdin (in this case, your keyboard).

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