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# LHB Linux Digest #26.15: Taming stderr, Cybersecurity Certification and More
- URL: https://linuxhandbook.com/newsletter/26-15/
- Published: 2026-10-16T12:34:23.000Z
- Updated: 2026-10-16T12:34:23.000Z
- Description: Errors are output too. Learn where they go.
- Author: Abhishek Prakash
- Tags: Newsletter

It's a security-heavy edition this time, and that's not entirely by design. October is Cybersecurity Awareness Month, a nasty VM escape bug just dropped, and the [Linux Foundation has a sale on its security certifications](https://www.awin1.com/cread.php?awinmid=85919&awinaffid=429005&ued=https%3A%2F%2Ftraining.linuxfoundation.org%2Foctober-2026-promo%2F&ref=linuxhandbook.com).

If you're still working through [Command Conqueror](https://linuxhandbook.com/ctf/command-conqueror/), you're already halfway into this world. Level 10 is privilege escalation after all. And I'm still waiting to hear how far you got 😉

And if cyber security is something that interests you, do try our '[Pentora Box](https://linuxhandbook.com/pentora-box/)' lab series. Basically, it has a collection of beginner-level pen-test scenarios that you can follow from your Linux system and do some hands-on practice.

## 🧵 Where does the output go?

Every command you run in Linux has two output channels. Standard output (stdout) carries the results. Standard error (stderr) carries the complaints. Both land on your screen, which is why they're so easy to confuse.

The difference shows up the moment you redirect. Run `find / -name "*.conf" > results.txt` and you'll still see a wall of "Permission denied" on your screen. That's because `>` only captures stdout. The errors went straight past it.

Each channel has a number. stdout is `1` and stderr is `2`. So `2>` redirects only the errors, and the classic way to silence them is to send them to [/dev/null](https://linuxhandbook.com/dev-null/), the black hole of Linux:

```bash
find / -name "*.conf" 2>/dev/null

```

Want both in the same file? Use `> file 2>&1`, which says "send stderr wherever stdout is going". Order matters here. `2>&1 > file` does not do the same thing, and it trips up a lot of people. The same trick works for [discarding all output with /dev/null](https://linuxhandbook.com/redirect-dev-null/) when you want a command to run silently.

And if you want to see the output and save it at the same time, use the [tee command](https://linuxhandbook.com/tee-command/). Our beginner's guide to [input, output and error redirection](https://linuxhandbook.com/redirection-linux/) covers all of this in more detail.

## 💡 Quick terminal tip

You can pipe the standard output and standard error of a command to pager directly using the `|&` operation.

```bash
find / -name "*.conf" |& less

```

The above command will pipe the found result as well as errors to a less pager. No need to redirect output to a file and then view its contents.

![](https://linuxhandbook.com/content/images/2026/10/pipe-errors-and-out-to-pager.gif)

## 🎓 Make your security skills official

[![Linux Foundation cybersecurity sale](https://linuxhandbook.com/content/images/2026/10/lf-cyber.webp)](https://www.awin1.com/cread.php?awinmid=85919&awinaffid=429005&ued=https%3A%2F%2Ftraining.linuxfoundation.org%2Foctober-2026-promo%2F&ref=linuxhandbook.com)

Security isn't just a job for the security team anymore. If you manage servers, containers or pipelines, you're expected to know how to lock them down. A certification is how you prove it to someone who's hiring.

The Linux Foundation is [running its Cybersecurity Awareness Month sale](https://www.awin1.com/cread.php?awinmid=85919&awinaffid=429005&ued=https%3A%2F%2Ftraining.linuxfoundation.org%2Foctober-2026-promo%2F&ref=linuxhandbook.com) with up to 40% off security certifications, courses and bundles. It runs until 23rd October only, so hurry up.

The CKS (Certified Kubernetes Security Specialist) is the obvious pick if you work with Kubernetes. Actually, you can bundle Kubernetes and Cloud Native Security Associate (KCSA) + Certified Kubernetes Security Specialist (CKS) certification exams for $387 instead of $645.

You can attempt the exams twice in the timeframe of 12 months. Get it today, prepare for the exam for a few months and then attempt your certification.

[Linux Foundation Cybersecurity Deals](https://www.awin1.com/cread.php?awinmid=85919&awinaffid=429005&ued=https%3A%2F%2Ftraining.linuxfoundation.org%2Foctober-2026-promo%2F&ref=linuxhandbook.com)

## 📦 Self-hosting: Flame

[Flame](https://github.com/pawelmalak/flame?ref=linuxhandbook.com) is a lightweight self-hosted start page that helps you organize bookmarks, services, and frequently used web apps from a single dashboard. It integrates well with Docker and makes managing homelab or self-hosted environments much more convenient through an easy-to-use web interface.

[GitHub - pawelmalak/flame: Flame is self-hosted startpage for your server. Easily manage your apps and bookmarks with built-in editors.Flame is self-hosted startpage for your server. Easily manage your apps and bookmarks with built-in editors. - pawelmalak/flame![](https://linuxhandbook.com/content/images/icon/favicon-ed4431a0-434d-4027-a57a-024d77313e6e.png)GitHub![](https://linuxhandbook.com/content/images/thumbnail/41e1c378-2d4a-4350-b432-b59abbc67c9f-5b5d96d5-d0d3-49f1-90bf-b84a896facfa)](https://github.com/pawelmalak/flame?ref=linuxhandbook.com)

## 🛠️ Tool discovery: cocoindex-code

[cocoindex-code](https://github.com/cocoindex-io/cocoindex-code?ref=linuxhandbook.com) is an AST-based semantic code search tool that helps AI coding agents find relevant code without repeatedly scanning an entire repository. By maintaining a lightweight local index, it reduces token usage and makes navigating large codebases significantly faster.

[GitHub - cocoindex-io/cocoindex-code: A super light-weight embedded code search engine CLI (AST based) that just works - improves speed and efficiency for coding agent 🌟 Star if you like it!A super light-weight embedded code search engine CLI (AST based) that just works - improves speed and efficiency for coding agent 🌟 Star if you like it! - cocoindex-io/cocoindex-code![](https://linuxhandbook.com/content/images/icon/favicon-bd089be5-20be-4a7e-a33e-de98229e4d58.png)GitHub![](https://linuxhandbook.com/content/images/thumbnail/cocoindex-code-430c8331-07c1-409c-a65a-38d3dbc43429)](https://github.com/cocoindex-io/cocoindex-code?ref=linuxhandbook.com)

## 📰 Linux news that matters

- [Microsoft has contributed a new hv-iommu-guest driver](https://www.phoronix.com/news/MS-Paravirt-Hyper-V-IOMMU?ref=linuxhandbook.com) targeted for the upcoming Linux 7.4 cycle, providing a para-virtualized IOMMU implementation for Linux guests running on Hyper-V.
- [Researchers disclosed PwnEscape (CVE-2026-99999)](https://thehackernews.com/2026/10/critical-pwnescape-linux-kernel.html?ref=linuxhandbook.com), a critical Linux kernel networking vulnerability that can allow code running inside a virtual machine to read host memory, crash the host, and potentially achieve host-level code execution.
- [The Linux kernel community has reached consensus](https://www.theregister.com/ai-and-ml/2026/10/14/linux-kernel-devs-drop-obligatory-confession-of-ai-tool-usage/5303140?ref=linuxhandbook.com) to deprecate the "Assisted-by" tag that asked contributors to disclose AI-assisted code generation in patch submissions.
- [Anthropic has launched OSS Scanner](https://www.helpnetsecurity.com/2026/10/09/anthropic-oss-scanner-ai-security-scans/?ref=linuxhandbook.com), a free service that periodically scans participating open-source projects using Claude models and sends maintainers vulnerability reports, reproduction details, and remediation suggestions.
- [GitHub introduced new fine-grained permissions](https://devops.com/github-narrows-app-permissions-to-pull-teams-off-classic-pats?ref=linuxhandbook.com), allowing automation to create repositories and manage app installations without requiring broad administrative privileges.
- [npm now automatically expires newly created trusted publishing configurations](https://devops.com/npm-puts-a-48-hour-clock-on-unused-trusted-publishing-configurations?ref=linuxhandbook.com) if they do not complete a successful publish within 48 hours of creation.

## 😂 Geek humor

![](https://linuxhandbook.com/content/images/2026/10/lhb-meme-oct-16.jpg)

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