Manual: opensnoop-bpfcc

opensnoop(8)					   System Manager's Manual					opensnoop(8)

NAME
       opensnoop - Trace open() syscalls. Uses Linux eBPF/bcc.

SYNOPSIS
       opensnoop [-h] [-T] [-U] [-x] [-p PID] [-t TID] [-u UID]
		    [-d DURATION] [-n NAME] [-e] [-f FLAG_FILTER] [-F]
		    [--cgroupmap MAPPATH] [--mntnsmap MAPPATH]

DESCRIPTION
       opensnoop  traces  the open() syscall, showing which processes are attempting to open which files. This can be useful
       for determining the location of config and log files, or for troubleshooting applications that are failing, specially
       on startup.

       This works by tracing the kernel sys_open() function using dynamic tracing, and	will  need  updating  to  match	 any
       changes to this function.

       This  makes  use	 of a Linux 4.4 feature (bpf_perf_event_output()); for kernels older than 4.4, see the version under
       tools/old, which uses an older mechanism.

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

REQUIREMENTS
       CONFIG_BPF and bcc.

OPTIONS
       -h     Print usage message.

       -T     Include a timestamp column.

       -U     Show UID.

       -x     Only print failed opens.

       -p PID Trace this process ID only (filtered in-kernel).

       -t TID Trace this thread ID only (filtered in-kernel).

       -u UID Trace this UID only (filtered in-kernel).

       -d DURATION
	      Total duration of trace in seconds.

       -n name
	      Only print processes where its name partially matches 'name'

       -e     Show extended fields.

       -f FLAG
	      Filter on open() flags, e.g., O_WRONLY.

       -F     Show full path for an open file with relative path.

       --cgroupmap MAPPATH
	      Trace cgroups in this BPF map only (filtered in-kernel).

       --mntnsmap  MAPPATH
	      Trace mount namespaces in this BPF map only (filtered in-kernel).

EXAMPLES
       Trace all open() syscalls:
	      # opensnoop

       Trace all open() syscalls, for 10 seconds only:
	      # opensnoop -d 10

       Trace all open() syscalls, and include timestamps:
	      # opensnoop -T

       Show UID:
	      # opensnoop -U

       Trace only open() syscalls that failed:
	      # opensnoop -x

       Trace PID 181 only:
	      # opensnoop -p 181

       Trace UID 1000 only:
	      # opensnoop -u 1000

       Trace all open() syscalls from processes where its name partially matches 'ed':
	      # opensnoop -n ed

       Show extended fields:
	      # opensnoop -e

       Only print calls for writing:
	      # opensnoop -f O_WRONLY -f O_RDWR

       Trace a set of cgroups only (see special_filtering.md from bcc sources for more details):
	      # opensnoop --cgroupmap /sys/fs/bpf/test01

FIELDS
       TIME(s)
	      Time of the call, in seconds.

       UID    User ID

       PID    Process ID

       TID    Thread ID

       COMM   Process name

       FD     File descriptor (if success), or -1 (if failed)

       ERR    Error number (see the system's errno.h)

       FLAGS  Flags passed to open(2), in octal

       PATH   Open path

OVERHEAD
       This traces the kernel open function and prints output for each event. As the rate of this is generally	expected  to
       be  low (< 1000/s), the overhead is also expected to be negligible. If you have an application that is calling a high
       rate of open()s, then test and understand overhead before use.

SOURCE
       This is from bcc.

	      https://github.com/iovisor/bcc

       Also look in the bcc distribution for a companion _examples.txt file containing example usage, output, and commentary
       for this tool.

OS
       Linux

STABILITY
       Unstable - in development.

AUTHOR
       Brendan Gregg, Rocky Xing

SEE ALSO
       execsnoop(8), funccount(1)

USER COMMANDS						 2020-02-20						opensnoop(8)