> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Tuesday, September 13, 2022 12:34 AM
> To: dev@dpdk.org
> Cc: Stephen Hemminger <stephen@networkplumber.org>; Kaur, Arshdeep
> <arshdeep.kaur@intel.com>
> Subject: [RFT] dumpcap: add file-prefix option
>
> When using dumpcap in container environment or with multiple DPDK
> processes, it is useful to be able to specify file prefix.
>
> This version only accepts the long format option used by other commands.
> If no prefix is specified then the default is used.
>
> Suggested-by: Arshdeep Kaur <arshdeep.kaur@intel.com>
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
> Did basic command line test, but still needs testing with a prefix being used
> (ie multiple apps).
>
>  app/dumpcap/main.c | 24 ++++++++++++++++++------
>  1 file changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/app/dumpcap/main.c b/app/dumpcap/main.c index
> a6041d4ff495..bdeef96d9c0b 100644
> --- a/app/dumpcap/main.c
> +++ b/app/dumpcap/main.c
> @@ -61,6 +61,7 @@ static char *output_name;  static const char
> *filter_str;  static unsigned int ring_size = 2048;  static const char
> *capture_comment;
> +static const char *file_prefix;
>  static uint32_t snaplen = RTE_MBUF_DEFAULT_BUF_SIZE;  static bool
> dump_bpf;  static struct { @@ -122,6 +123,7 @@ static void usage(void)
>              "                           add a capture comment to the output file\n"
>              "\n"
>              "Miscellaneous:\n"
> +            "  --file-prefix=<prefix>   prefix to use for multi-process\n"
>              "  -q                       don't report packet capture counts\n"
>              "  -v, --version            print version information and exit\n"
>              "  -h, --help               display this help and exit\n"
> @@ -310,6 +312,7 @@ static void parse_opts(int argc, char **argv)
>       static const struct option long_options[] = {
>               { "autostop",        required_argument, NULL, 'a' },
>               { "capture-comment", required_argument, NULL, 0 },
> +             { "file-prefix",     required_argument, NULL, 0 },
>               { "help",            no_argument,       NULL, 'h' },
>               { "interface",       required_argument, NULL, 'i' },
>               { "list-interfaces", no_argument,       NULL, 'D' },
> @@ -330,11 +333,13 @@ static void parse_opts(int argc, char **argv)
>
>               switch (c) {
>               case 0:
> -                     switch (option_index) {
> -                     case 0:
> +                     if (!strcmp(long_options[option_index].name,
> +                                 "capture-comment")) {
>                               capture_comment = optarg;
> -                             break;
> -                     default:
> +                     } else if (!strcmp(long_options[option_index].name,
> +                                        "file-prefix")) {
> +                             file_prefix = optarg;
> +                     } else {
>                               usage();
>                               exit(1);
>                       }

parse_opts() is called after dpdk_init(). So whatever file-prefix we provide, for eal init, it remains NULL.
Please let me know your thoughts about it.

> @@ -512,12 +517,14 @@ static void dpdk_init(void)
>       static const char * const args[] = {
>               "dumpcap", "--proc-type", "secondary",
>               "--log-level", "notice"
> -
>       };
> -     const int eal_argc = RTE_DIM(args);
> +     int eal_argc = RTE_DIM(args);
>       char **eal_argv;
>       unsigned int i;
>
> +     if (file_prefix != NULL)
> +             eal_argc += 2;
> +
>       /* DPDK API requires mutable versions of command line arguments.
> */
>       eal_argv = calloc(eal_argc + 1, sizeof(char *));
>       if (eal_argv == NULL)
> @@ -527,6 +534,11 @@ static void dpdk_init(void)
>       for (i = 1; i < RTE_DIM(args); i++)
>               eal_argv[i] = strdup(args[i]);
>
> +     if (file_prefix != NULL) {
> +             eal_argv[i++] = strdup("--file-prefix");
> +             eal_argv[i++] = strdup(file_prefix);
> +     }
> +
>       if (rte_eal_init(eal_argc, eal_argv) < 0)
>               rte_exit(EXIT_FAILURE, "EAL init failed: is primary process
> running?\n");
>
> --
> 2.35.1