Man pages sections > man8 > ttysnoop-bpfcc

ttysnoop - Watch output from a tty or pts device. Uses Linux eBPF/bcc.

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

NAME

ttysnoop - Watch output from a tty or pts device. Uses Linux eBPF/bcc.

SYNOPSIS

ttysnoop [-h] [-C] device

DESCRIPTION

ttysnoop watches a tty or pts device, and prints the same output that is appearing on that device. It can be used to mirror the output from a shell session, or the system console.
 
This works by use of kernel dynamic tracing of the tty_write() function. This tool will need updating in case that kernel function changes in a future kernel version.
 
Since this uses BPF, only the root user can use this tool.

REQUIREMENTS

CONFIG_BPF and bcc.

OPTIONS

-C
Don't clear the screen.
device
Either a path to a tty device (eg, /dev/tty0) or a pts number (eg, the "3" from /dev/pts/3).

EXAMPLES

Snoop output from /dev/pts/2
# ttysnoop /dev/pts/2
Snoop output from /dev/pts/2 (shortcut)
# ttysnoop 2
Snoop output from the system console
# ttysnoop /dev/console
Snoop output from /dev/tty0
# ttysnoop /dev/tty0

OVERHEAD

As the rate of tty_write() is expected to be very low (<100/s), the overhead of this tool is expected to be negligible.

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

opensnoop(1)
2016-02-08 USER COMMANDS