ykman assumes that pkill is available at /usr/bin/pkill

[colonelpanic8]

• YubiKey Manager (ykman) version: 4.0.3
• How was it installed?:
• Operating system and version: NixOS

Steps to reproduce

Perform an openpgp reset

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/bin/.ykman-wrapped", line 9, in <module>
    sys.exit(main())
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/lib/python3.8/site-packages/ykman/cli/__main__.py", line 371, in main
    cli(obj={})
  File "/nix/store/wj2z6qly1qjhw2fjliyxk12vb45i873x-python3.8-click-8.0.1/lib/python3.8/site-packages/click/core.py", line 1137, in __call__
    return self.main(*args, **kwargs)
  File "/nix/store/wj2z6qly1qjhw2fjliyxk12vb45i873x-python3.8-click-8.0.1/lib/python3.8/site-packages/click/core.py", line 1062, in main
    rv = self.invoke(ctx)
  File "/nix/store/wj2z6qly1qjhw2fjliyxk12vb45i873x-python3.8-click-8.0.1/lib/python3.8/site-packages/click/core.py", line 1668, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/nix/store/wj2z6qly1qjhw2fjliyxk12vb45i873x-python3.8-click-8.0.1/lib/python3.8/site-packages/click/core.py", line 1668, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/nix/store/wj2z6qly1qjhw2fjliyxk12vb45i873x-python3.8-click-8.0.1/lib/python3.8/site-packages/click/core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/nix/store/wj2z6qly1qjhw2fjliyxk12vb45i873x-python3.8-click-8.0.1/lib/python3.8/site-packages/click/core.py", line 763, in invoke
    return __callback(*args, **kwargs)
  File "/nix/store/wj2z6qly1qjhw2fjliyxk12vb45i873x-python3.8-click-8.0.1/lib/python3.8/site-packages/click/decorators.py", line 26, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/lib/python3.8/site-packages/ykman/cli/openpgp.py", line 123, in reset
    ctx.obj["controller"].reset()
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/lib/python3.8/site-packages/ykman/cli/util.py", line 164, in __getitem__
    self.resolve()
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/lib/python3.8/site-packages/ykman/cli/util.py", line 161, in resolve
    self._objects[k] = f()
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/lib/python3.8/site-packages/ykman/cli/__main__.py", line 299, in <lambda>
    ctx.obj.add_resolver("conn", lambda: resolve()[0])
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/lib/python3.8/site-packages/ykman/cli/__main__.py", line 294, in resolve
    items = _run_cmd_for_single(ctx, subcmd.name, connections, reader)
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/lib/python3.8/site-packages/ykman/cli/__main__.py", line 190, in _run_cmd_for_single
    return retrying_connect(None, connections, state=state)
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/lib/python3.8/site-packages/ykman/cli/__main__.py", line 88, in retrying_connect
    return connect_to_device(serial, connections)
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/lib/python3.8/site-packages/ykman/device.py", line 216, in connect_to_device
    conn = dev.open_connection(connection_type)
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/lib/python3.8/site-packages/ykman/pcsc/__init__.py", line 87, in open_connection
    return self._open_smartcard_connection()
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/lib/python3.8/site-packages/ykman/pcsc/__init__.py", line 97, in _open_smartcard_connection
    if kill_scdaemon():
  File "/nix/store/0cbrbj87gbpjy8g1liv5dda7jbcxp10m-python3.8-yubikey-manager-4.0.3/lib/python3.8/site-packages/ykman/pcsc/__init__.py", line 142, in kill_scdaemon
    return_code = subprocess.call(["/usr/bin/pkill", "-9", "scdaemon"])  # nosec
  File "/nix/store/6cfajs6lsy9b4wxp3jvyyl1g5x2pjmpr-python3-3.8.9/lib/python3.8/subprocess.py", line 340, in call
    with Popen(*popenargs, **kwargs) as p:
  File "/nix/store/6cfajs6lsy9b4wxp3jvyyl1g5x2pjmpr-python3-3.8.9/lib/python3.8/subprocess.py", line 858, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/nix/store/6cfajs6lsy9b4wxp3jvyyl1g5x2pjmpr-python3-3.8.9/lib/python3.8/subprocess.py", line 1704, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: '/usr/bin/pkill'
imalison@ryzen-shine:~/ > ykman version
Usage: ykman [OPTIONS] COMMAND [ARGS]...
Try 'ykman -h' for help.

This is not good behavior. pkill will not always be available at /usr/bin, and it should look in $PATH to find it.