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A comment on Unix's special way of marking login shells goes back to V2 Unix (at least). Parent comment

Re:Unix's special way of marking login shells goes back to V... by tinus_hn on Sunday December 11, 2022 @05:31PM (#33948298)
Obviously permanently wasting memory on fragmentation is not an option on a device that typically has 24kb memory. Especially not just so you can specify long filenames for the shell, when the filesystem doesn’t even support those filenames.
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Re:Unix's special way of marking login shells goes back to V... by kragen on Monday December 12, 2022 @03:05PM (#33959478)
the alternative they chose was to permanently waste memory on fixed-size struct fields, so i guess it was actually an option

malloc on the pdp-11 never compacted of course

the filesystem supported 14 characters for the basename, but evidently we're talking about code with a 14-character limit on the pathname, not the basename

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Re:Unix's special way of marking login shells goes back to V... by tinus_hn on Tuesday December 13, 2022 @08:23AM (#33968473)
You don’t need compaction to reuse fixed size structures. I presume their priorities were with creating a working system, not one that answers to the ‘requirements’ of 50 years into the future.
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Re:Unix's special way of marking login shells goes back to V... by kragen on Thursday December 15, 2022 @01:59AM (#33996210)
you don't need compaction to reuse heap-allocated memory either

wasted memory due to heap fragmentation is very similar to wasted memory due to slack space in fixed-size structure fields

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