catp

Print the output of a running process

catp 0.2.0
Print the output of a running process

USAGE:
    catp [OPTIONS] <PID>

ARGS:
    <PID>    PID of the process to print

OPTIONS:
    -h, --help       Print help information
    -v, --verbose    Print more verbose information to stderr
    -V, --version    Print version information

Why

Sometimes a process is redirected to /dev/null because we don't expect to check its output. However, we may regret that decision and don't want to restart the process.

Or we just don't know where a running process is printing to.

Then just type catp!

How It Works

catp uses ptrace to intercept syscall and extracts data from the syscall write. So it should work for most applications. Since it slows down the syscall, it may impact the performance of IO-sensitive applications.

catp requires ptrace privilege to run, which in most systems means root.

Get Started

Download the binary from release. The one with gnu should work with a really recent glibc version. If that's not working, try the musl one.

Platform

Currently only x86_64 Linux is supported.