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In x | y, why is there a sub-shell created? For my understanding, when bash sees a pipe, it executes pipe() system call, that returns two fds. Now, command_left is execed and the output is fed to command_right as input. Now, command_right is execed. So, why is BASHPID different each time?

Abhijeet Rastogi
– Abhijeet Rastogi

2013-09-03 05:21:41 +00:00
Commented Sep 3, 2013 at 5:21
2

@shadyabhi It's simple - x and y are 2 separate commands running in 2 separate processes, so you have 2 separate subshells. If x runs in the same process as the shell, that means x must be a built-in.

jw013
– jw013

2013-09-03 20:59:55 +00:00
Commented Sep 3, 2013 at 20:59

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