# catp

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Print the output of *a running process*

![screenshot](docs/img/screenshot.png)

```plain
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.

## Platform

Currently only x86_64 Linux is supported.