Question

For my Java apps with very long classpaths, I cannot see the main class specified near the end of the arg list when using ps. I think this stems from my Ubuntu system’s size limit on /proc/pid/cmdline. How can I increase this limit?

Answer 1

You can’t change this dynamically, the limit is hard-coded in the kernel to PAGE_SIZE in fs/proc/base.c:

 274        int res = 0;  275        unsigned int len;  276        struct mm_struct *mm = get_task_mm(task);  277        if (!mm)  278                goto out;  279        if (!mm->arg_end)  280                goto out_mm;    /* Shh! No looking before we're done */  281  282        len = mm->arg_end - mm->arg_start;  283   284        if (len > PAGE_SIZE)  285                len = PAGE_SIZE;  286   287        res = access_process_vm(task, mm->arg_start, buffer, len, 0);