Listing Full Command Line on HP-UX

There is one very annoying limitation on HP-UX - there is no /proc folder and ps command can display maximum 63 characters from processes command line. There is no simple way how to display full command line of a specified process.

If you're working with Java programs, you know, that the first 63 characters barely reach the classpath definition. Usually it's just the path to the java binary.

Yesterday I needed to find out, if one java program is not running multiple times. And guess what, it's almost impossible to find out on a server with tens of different java programs running. After lot of searching I came up with this program - it lists all the running process ids and their respective command lines. There is no original code happening, it's basically, this forum post merged with this manual page.

#include <stdio.h>
#include <sys/pstat.h>
#include <sys/pstat/pstat_ops.h>
#define BURST 20
#define MAX_LENGTH 1024

struct pst_status pst[BURST];

int main(void)
{
char command [MAX_LENGTH];
        union pstun pu;

        int i, count;
        int idx = 0;/* index within the context */
        /* loop until count == 0, will occur all have been returned */

        while ((count=pstat_getproc(pst, sizeof(pst[0]),BURST,idx))>0)
        {
                for (i = 0; i < count; i++)
                {
                        pu.pst_command = command;
                        if (pstat(PSTAT_GETCOMMANDLINE, pu, MAX_LENGTH, 1, pst[i].pst_pid) == -1)
                        {
                                printf("ERROR: failure using pid(%d)\n", pst[i].pst_pid);
                                exit(-1);
                        }
                        printf("%d: %s\n",  pst[i].pst_pid, pu.pst_command);
                }
                idx = pst[count-1].pst_idx + 1;
        }

        if (count == -1)
                perror("pstat_getproc()");
}

Compile the code with the following command

cc pstat.c -o pstat +DD64

You have to include the +DD64 if you're on a 64bit system. Otherwise, you'll get following error:

pstat_getproc(): Value too large to be stored in data type

Of course, about five seconds after finishing this article I found a way how to do it with the original HP-UX ps command, so please disregard my blabbering :)

ps -exx