NAME

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

SYNOPSIS

       opensnoop [-h] [-T] [-x] [-p PID] [-t TID] [-n name]

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 4.5 feature (bpf_perf_event_output()); for kernels  older  than  4.5,  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.

       -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).

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

EXAMPLES

       Trace all open() syscalls:
              # opensnoop

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

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

       Trace PID 181 only:
              # opensnoop -p 181

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

FIELDS

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

       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)

       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

SEE ALSO

       funccount(1)