Redirect a Service Output to a File

Introduction

It can be useful to redirect a program's output to a file. Here's how to do it.

Usage

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yes 'Y'|gdb -ex 'p close(1)' -ex 'p creat("/tmp/output.txt",0600)' -ex 'q' -p pid

This command uses the GDB debugger to attach to a running process and reassign the file handle to a file.

The two commands executed in GDB are:

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p close(1) which closes STDOUT

and

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p creat("/tmp/filename",0600)

which creates a file and opens it for output to which the process will be assigned.

Sequentially, this command closes the STDOUT file handle, creates a new output file, and captures the output to this file.