The man page does explain what the bracket-braces means (it refers to threads), but I'm wondering what just the braces means.
From this here I can see that auditd
and node
are like this.
❯ pstree
init─┬─agetty
├─atd
├─auditd───{auditd}
├─crond
├─dbus-daemon
├─dhclient
├─6*[mingetty]
├─ntpd
├─rsyslogd───3*[{rsyslogd}]
├─2*[sendmail]
├─sshd─┬─sshd───sshd───zsh───tmux
│ └─sshd───sshd───zsh───man───sh───sh───less
├─tmux─┬─2*[zsh]
│ ├─zsh───node───{node}
│ └─zsh───pstree
└─udevd───2*[udevd]
My current best guess is that it means they are blocked on input.