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psc: The ps utility, with an eBPF twist and container context

  # Find processes connected to a specific port
  psc 'socket.dstPort == uint(443)'

  # Filter by PID range
  psc 'process.pid > 1000 && process.pid < 2000'
It seems weird to require the user to remember that ports have to be marked uint when it doesn't look like anything else does.
Thanks for including so many examples! Perhaps include one example output. Other than mention of the optional '--tree' parameter, it's unclear if the default result would be a list, table, JSON, etc.
  • WD-42
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  • 1 hour ago
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This is neat but the examples comparing the tool against piping grep seem to counter the argument to me. A couple of pipes to grep seems much easier to remember and type, especially with all the quotes needed for psc. For scripts where you need exact output this looks great.
I’m the opposite - I much prefer a structured query language (ahem) for this type of thing. If I’m looking at someone’s (ie my own 6 months later) script I much prefer to see the explicit structure being queried vs “why are we feeling for foo or grabbing the 5th field based on squashed spaces as the separater”.

Nice use of CEL too. Neat all around.

I'm not convinced with the need to embed CEL. You could just output json and pipe to jq.
Sounds less efficient in both space and time.
An unfortunate name that triggers everybody who’s ever worked at Meta :)
> psc uses eBPF iterators to read process and file descriptor information directly from kernel data structures. This bypasses the /proc filesystem entirely, providing visibility that cannot be subverted by userland rootkits or LD_PRELOAD tricks.

Is there a trade off here?

I found this justification dubious. To me the main reason to use eBPF is that it gives more information and is lower overhead.
It requires root
Running eBPF programs doesn't strictly require root.
It requires cap_bpf which is considered a high privileged capability.

So yes, it requires root in the sense of what people mean by root.

Their first example is bad:

    ps aux | grep nginx | grep root | grep -v grep
can be done instead (from memory, not at a Linux machine ATM):

    ps -u root -C nginx
which is arguably better than their solution:

    psc 'process.name == "nginx" && process.user == "root"'
The commands in their example are not equivalent. The ps | grep thing searches the full command line including argument while ps -C (and, presumably, the psc thing) just returns the process name.

Should you for some reason want to do the former, this is easiest done using:

  pgrep -u root -f nginx
which exists on almost all platforms, with the notable exception of AIX.

Their other slightly convoluted example is:

  psc 'socket.state == established && socket.dstPort == uint(443)'
which is much more succinct with:

  lsof -i :443 -s TCP:ESTABLISHED