[TUHS] Who came up with the spell check pipeline?

[Heinz Lycklama via TUHS]

Grok provides a meaningful answer.
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Brian Kernighan is credited with demonstrating the famous spell checking 
pipeline using Unix commands like cat | tr | sort | uniq | comm (or 
similar variations). In a classic 1970s Bell Labs video titled "The UNIX 
Operating System," he showcased pipelines for spell checking as an early 
example of Unix's power. The video uses a pipeline like makewords 
sentence | lowercase | sort | unique | mismatch to extract words, 
lowercase them, sort, remove duplicates, and compare against a 
dictionary—concepts that directly inspired modern equivalents with tr 
for translation, uniq for deduplication, and comm for comparison. This 
approach highlights Unix's philosophy of combining simple tools for 
complex tasks, and while the exact commands evolved, the core idea stems 
from Kernighan's presentation. The original spell command from 1975, 
written by Stephen C. Johnson with improvements by Douglas McIlroy, used 
a similar internal logic but not this exact pipeline.
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Heinz

On 9/3/2025 5:53 AM, Dan Cross via TUHS wrote:
> On Wed, Sep 3, 2025 at 3:47 AM Diomidis Spinellis via TUHS
> <tuhs at tuhs.org> wrote:
>> In Brian Kernighan's amazing VCF talk that Arnold Robbins shared
>> yesterday, bwk mentions that Steve N[uancen?] came up with the famous
>> spell checking pipeline: cat | tr | sort | uniq | comm
>>
>> https://www.youtube.com/watch?v=WEb_YL1K1Qg&t=1396s
>>
>> Anybody knows the correct name of that person?  ChatGPT only
>> hallucinates many wrong ones.
> As others have pointed out, it was Steve Johnson.  I wanted to mention
> that he did say Steve Johnson in the video as well, though I can see
> how one might (mis)hear differently; I think that's just an artifact
> of the audio.
>
>          - Dan C.
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