症状很简单。例如：
ls | grep a | grep b | grep c | grep d
投掷
-bash: child setpgid (8948 to 8943): Operation not permitted
-bash: child setpgid (8950 to 8943): Operation not permitted
-bash: child setpgid (8952 to 8943): Operation not permitted
-bash: child setpgid (8953 to 8943): Operation not permitted
-bash: child setpgid (8954 to 8943): Operation not permitted
-bash: child setpgid (8955 to 8943): Operation not permitted
-bash: child setpgid (8962 to 8957): Operation not permitted
-bash: child …