13:20 <aryehw> hello,

13:21 <aryehw> had a question regarding the cmdline_str function

13:21 <aryehw> https://sourceware.org/systemtap//tapsets/API-cmdline-str.html

13:22 <aryehw> many times it fails to give me the correct args and returns a sequence of empty strings like: "" "" "" "" ""

13:23 <aryehw> sometimes on my server the list is long too

13:24 <aryehw> is this expected and any ideas on why I am seeing this?

13:28 <aryehw> Heres's an example, when I run:

13:28 <aryehw> stap -e 'probe syscall.execve{println(name, ":", argstr);println("cmdline_str:",cmdline_str())}'

13:29 <aryehw> I can get:

13:29 <aryehw> execve:"/usr/libexec/postfix/pickup", ["pickup", "-l", "-t", "fifo", "-u"], ["MAIL_CONFIG=/etc/postfix", "MAIL_LOGTAG=postfix", "LANG=C", "GENERATION=24"]

13:29 <aryehw> cmdline_str: "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" ""

13:39 <mjw> I believe the execve and cmdline_str arguments are for different processes.

13:39 <mjw> the execve is for the to be created process

13:39 <mjw> the cmdline_str is for the current process calling execve

13:39 <mjw> I don't know why the command line string isn't available (anymore) for the current process though.

13:44 <aryehw> execve was just an example for a probe

13:44 <aryehw> happens also with syscall.clone for example

13:45 <aryehw> stap 'probe syscall.clone{println(name, ":", argstr);println("cmdline_str:",cmdline_str())}'

13:45 <aryehw> clone:CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, 0x7ffe6732a860, 0x0, 0x7fc6200719d0

13:45 <aryehw> cmdline_str: "" "" "" ""