bash - why $BASH_SUBSHELL doesn't increase in pipe -
i know pipe create subshell.
i test $bash_subshell , $bashpid , , find $bash_subshell doesn't increase in pipe
echo $bash_subshell # 0 echo $bashpid # 8347 echo $bash_subshell | cat # 0 echo $bashpid | cat # 9727 (echo $bash_subshell) # 1 (echo $bashpid) # 9778
when bash merely forks, sets command , execves it, doesn't count subshell.
for kind of control structure, command groups, if statements , while loops, shell has involved beyond setup, does.
this apparent bash source, execute_command_internal in execute_cmd.c.
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