Tips on Unix utilities and related topics from @JohnDCook.

Joined August 2011
Unix tool tip retweeted
Now I just think of this old guy whenever I use tar. That’s how I remember it.
How long have you been using Linux? 20 years. So you must be good with tar commands?
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Linux pros and cons
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Unpacking a bash brace expansion example by @pkrumins johndcook.com/blog/2026/06/2…
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people are making memes of @ZackKorman now
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folder or directory
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I talked to a man yesterday who has 5 virtual assistants. I only have two: Python and Bash. I used to have a virtual assistant named Perl but I had to let her go. I got along with her OK but not the rest of my staff.
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Ali Spittel
@ASpittelApr 15
cron jobs are going through the most epic rebrand
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Unix tool tip retweeted
Unix once featured possibly the greatest—and creepiest—Easter egg of all time. In some early AT&T Unix versions, typing the username “dmr” (Dennis MacAlistair Ritchie’s initials) at login triggered the message: “Dennis Ritchie has retired, please use another login.” Even years after his death, this hidden joke occasionally resurfaced, prompting new admins into panicked midnight Google sessions. Call it Ritchie’s mischievous sense of humor reaching beyond the grave—or perhaps Unix’s quirky personality revealing itself. Either way, sysadmins everywhere learned an important lesson: Unix geeks love nothing better than trolling the unsuspecting.
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UNIX was built in one month. Ken Thompson's wife took their son on vacation. He had 3 weeks alone. He wrote the kernel in week 1, the shell in week 2, the editor in week 3. Modern dev teams spend 3 weeks in sprint planning.
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Unix’s elegant pipe operator (|)—allowing sysadmins to effortlessly chain commands together—was invented largely because of programmer laziness. Douglas McIlroy, fed up with writing tedious intermediate files and shuffling data manually, demanded a simpler solution. His colleagues at Bell Labs grudgingly obliged, introducing the pipe as an inter-process communication mechanism. Laziness triumphed spectacularly: pipes not only saved effort, but also became a cornerstone of Unix’s elegant modular design philosophy. Decades later, we have sysadmins piping commands together into monstrous, unmaintainable one-liners—exactly as McIlroy intended.
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incredible that we built all this RAG and vector database stuff and it turns out that grep from 1973 works better than all that
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I really loved this book as a teenager getting into Linux. Now, every time I ask Amp to create a one-liner for me, I think of it.
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Crazy how the UNIX core tools were ready for this since the 1970s.
Almost any software that does not work well with AI agents, is not going to make it. I’m using a lot of tools with tons of UI, all of it will either have to be rewritten to be agent friendly, or it’s dead. For a lot of it too, slapping some MCP on it won’t be enough either.
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We should create some form of distributed version control system so this can’t happen
grim
@grimcodes12 Oct 2025
My github account is suspended??
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Legend has it gym memberships are particularly hard to cancel here because nobody knows how to exit
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Base58 versus Base85 encoding johndcook.com/blog/2025/07/2…
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German ergonomic workstation concept from 1969.
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