bionic (8) opensnoop-perf.8.gz

NAME

       opensnoop - trace open() syscalls with file details. Uses Linux ftrace.

SYNOPSIS

       opensnoop [-htx] [-d secs] [-p pid] [-L tid] [-n name] [filename]

DESCRIPTION

       This traces open() syscalls, showing the file name (pathname) and returned file descriptor number (or -1,
       for error).

       This implementation is designed to work on older kernel versions, and without kernel debuginfo. It  works
       by  dynamic  tracing  of the return value of getname() as a string, and associating it with the following
       open() syscall return.  This approach is kernel version specific, and may not work on your  version.   It
       is a workaround, and proof of concept for ftrace, until more kernel tracing functionality is available.

       Since this uses ftrace, only the root user can use this tool.

REQUIREMENTS

       FTRACE  and  KPROBE CONFIG, the syscalls:sys_exit_open tracepoint, and the getname() kernel function. You
       may already have these enabled and available on recent Linux kernels. And awk.

OPTIONS

       -d secs
              Set the duration of tracing, in seconds. Trace output will be buffered and  printed  at  the  end.
              This also reduces overheads by buffering in-kernel, instead of printing events as they occur.

              The  ftrace buffer has a fixed size per-CPU (see /sys/kernel/debug/tracing/buffer_size_kb). If you
              think events are missing, try increasing that size.

       -h     Print usage message.

       -n name
              Only show processes matching this process  name.  Partial  strings  and  regular  expressions  are
              allowed. This is post-filtered using awk.

       -p PID Only trace this process ID. This is filtered in-kernel.

       -L TID Only trace this thread ID. This is filtered in-kernel.

       -t     Include timestamps, in seconds.

       -x     Only print failed open()s.

       filename
              Only  show open()s which match this filename. Partial strings and regular expressions are allowed.
              This is post-filtered using awk.

EXAMPLES

       Trace all open() syscalls with details:
              # opensnoop

       Only trace open()s for PID 81:
              # opensnoop -p 81

       Trace failed open() syscalls:
              # opensnoop -x

       Trace open() syscalls for filenames containing "conf":
              # opensnoop conf

       Trace open() syscalls for filenames ending in "log":
              # opensnoop 'log$'

FIELDS

       TIMEs  Time of open() completion, in units of seconds.

       COMM   Process name (if known).

       PID    Process ID.

       FD     File descriptor. If this is a successful open, the file descriptor number is  shown.  If  this  is
              unsuccessful, -1 is shown. Numbers beginning with 0x are hexadecimal.

       FILE   Filename (pathname) used by the open() syscall.

OVERHEAD

       This  reads and open() syscalls and getname() kernel functions as they occur.  For high rates of opens (>
       500/s), the overhead may begin to be measurable.  Test yourself. You  can  use  the  -d  mode  to  buffer
       output, reducing overheads.

SOURCE

       This is from the perf-tools collection.

              https://github.com/brendangregg/perf-tools

       Also  look  under the examples directory for a text file containing example usage, output, and commentary
       for this tool.

OS

       Linux

STABILITY

       Unstable - in development.

AUTHOR

       Brendan Gregg

SEE ALSO

       execsnoop(8), strace(1)