There's nothing specifically bash about it, but here's what the components mean:
"kill" = kill running process
"-9" = kill as forcefully as possible
"$(...)" = command substitution: run the stuff inside the brackets and replace this term with the results (it will be the processes to kill in this case).
"lsof" = list open files (other things like ports and devices count as files on Unix systems)
"-i" = search for internet address
":19421" = local machine, port 19421
I think they're missing a "-t" on lsof, to make it output process IDs only ("terse mode") instead of a human-readable table:
There's nothing specifically bash about it, but here's what the components mean:
"kill" = kill running process
"-9" = kill as forcefully as possible
"$(...)" = command substitution: run the stuff inside the brackets and replace this term with the results (it will be the processes to kill in this case).
"lsof" = list open files (other things like ports and devices count as files on Unix systems)
"-i" = search for internet address
":19421" = local machine, port 19421
I think they're missing a "-t" on lsof, to make it output process IDs only ("terse mode") instead of a human-readable table:
That "command substitution" bit will fail on tcsh, say, last I checked.
Is lsof part of the default install of OSX? It isn't usually part of the base install on Linux (though obviously very easy to install)
although command substitution is in the POSIX sh spec and so not a bashism, $(...) doesn't work in e.g. fish
that works on all korn shell based posix shells.