+/*?
+ * This command is used to start or stop a packet capture, or show
+ * the status of packet capture.
+ *
+ * This command has the following optional parameters:
+ *
+ * - <b>on|off</b> - Used to start or stop a packet capture.
+ *
+ * - <b>max <nn></b> - Depth of local buffer. Once '<em>nn</em>' number
+ * of packets have been received, buffer is flushed to file. Once another
+ * '<em>nn</em>' number of packets have been received, buffer is flushed
+ * to file, overwriting previous write. If not entered, value defaults
+ * to 100. Can only be updated if packet capture is off.
+ *
+ * - <b>intfc <interface>|any</b> - Used to specify a given interface,
+ * or use '<em>any</em>' to run packet capture on all interfaces.
+ * '<em>any</em>' is the default if not provided. Settings from a previous
+ * packet capture are preserved, so '<em>any</em>' can be used to reset
+ * the interface setting.
+ *
+ * - <b>file <name></b> - Used to specify the output filename. The file will
+ * be placed in the '<em>/tmp</em>' directory, so only the filename is
+ * supported. Directory should not be entered. If file already exists, file
+ * will be overwritten. If no filename is provided, '<em>/tmp/vpe.pcap</em>'
+ * will be used. Can only be updated if packet capture is off.
+ *
+ * - <b>status</b> - Displays the current status and configured attributes
+ * associated with a packet capture. If packet capture is in progress,
+ * '<em>status</em>' also will return the number of packets currently in
+ * the local buffer. All additional attributes entered on command line
+ * with '<em>status</em>' will be ingnored and not applied.
+ *
+ * @cliexpar
+ * Example of how to display the status of a tx packet capture when off:
+ * @cliexstart{pcap tx trace status}
+ * max is 100, for any interface to file /tmp/vpe.pcap
+ * pcap tx capture is off...
+ * @cliexend
+ * Example of how to start a tx packet capture:
+ * @cliexstart{pcap tx trace on max 35 intfc GigabitEthernet0/8/0 file vppTest.pcap}
+ * pcap tx capture on...
+ * @cliexend
+ * Example of how to display the status of a tx packet capture in progress:
+ * @cliexstart{pcap tx trace status}
+ * max is 35, for interface GigabitEthernet0/8/0 to file /tmp/vppTest.pcap
+ * pcap tx capture is on: 20 of 35 pkts...
+ * @cliexend
+ * Example of how to stop a tx packet capture:
+ * @cliexstart{vppctl pcap tx trace off}
+ * captured 21 pkts...
+ * saved to /tmp/vppTest.pcap...
+ * @cliexend
+?*/