3182da3965
Claude Code keeps per-project memory at <home>/.claude/projects/<key>/,
where <key> is the project's absolute path with every separator and the
drive colon turned into a dash. That makes it both rename-fragile and
machine-specific, and this project has hit each of those once:
- D:\DEV\Schunix -> D:\DEV\SchOS changed the key, and 43 memories were
invisible until moved across by hand.
- Development happens from Windows and from Linux, and each looks in a
different place for the same checkout.
Committing .claude/memory/ fixes both -- git carries it across renames
and between hosts -- and `import` puts it wherever the local machine
expects. .claude/settings.local.json stays ignored: those are per-machine
permissions.
The colon maps to a dash rather than being dropped. Deleting it gives
D-DEV-SchOS, which matches nothing and silently finds zero memories; that
was the first attempt. On Git Bash the key comes from `cygpath -w`,
because Claude Code is a Windows program and sees D:\DEV\SchOS, not
/d/DEV/SchOS.
34 lines
1.5 KiB
Markdown
34 lines
1.5 KiB
Markdown
---
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name: schunix-tty-fg-pgrp-coupling
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description: TIOCGPGRP and getpgrp() must agree or the shell spins forever at startup
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metadata:
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node_type: memory
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type: project
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originSessionId: d1a1ea76-f919-411c-b0ef-0e1bc5064563
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modified: 2026-08-01T19:01:09.569Z
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---
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`tcgetpgrp()` (TIOCGPGRP in `kernel/sys/sys_fs.c`) and `getpgrp()` must return
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the same value, or mksh hangs at startup in its standard loop:
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```c
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while (tcgetpgrp(tty) != getpgrp()) kill(0, SIGTTIN);
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```
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**Why this is a trap:** both used to answer `proc->pid` independently, so they
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agreed *by accident*. The moment `getpgrp()` started reporting a real process
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group (which a process inherits from its parent, so pid != pgid), they
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disagreed permanently and the shell spun — RUNNING, never printing a prompt,
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never exiting, with no error anywhere.
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Fixed 2026-08-01 by adding `tty_fg_pgrp` (defined in `kernel/core/console.c`,
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declared in `defs.h`), initialised to 1 so the first shell — which inherits
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init's group — sees itself as foreground. TIOCGPGRP reads it, TIOCSPGRP writes
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it. Anything that changes process-group semantics must keep these coupled.
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**Diagnosing this class of hang:** Ctrl-P over the serial console dumps the
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process table (`procdump`, wired up in `console.c`). A shell shown as `run`
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rather than `sleep` means a busy loop in userland, not a crash — and if
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`exit()` is never reached, nothing is dying, so look for a spin, not a fault.
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See [[schunix-verify-by-driving-shell]], [[schunix-rewrite-priorities]].
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