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89 lines
2.6 KiB
Markdown
89 lines
2.6 KiB
Markdown
[← Home](../README.md) · [AmigaDOS](README.md)
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# Process Management — CreateNewProc, SystemTagList, Execute
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## Overview
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AmigaDOS provides several ways to launch child processes, ranging from the low-level `CreateNewProc` to the shell-level `Execute` and `SystemTagList`.
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---
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## CreateNewProcTags (OS 2.0+)
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```c
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/* dos/dostags.h — NDK39 */
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struct Process *proc = CreateNewProcTags(
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NP_Entry, myFunction, /* function pointer */
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NP_Name, "Worker", /* task name */
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NP_StackSize, 8192, /* stack size in bytes */
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NP_Priority, 0, /* scheduling priority */
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NP_Input, Open("NIL:", MODE_OLDFILE),
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NP_Output, Open("NIL:", MODE_NEWFILE),
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NP_CloseInput, TRUE, /* close input on exit */
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NP_CloseOutput, TRUE,
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NP_CurrentDir, DupLock(currentDir),
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TAG_DONE);
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```
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### Tag Constants
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| Tag | Value | Meaning |
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|---|---|---|
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| `NP_Entry` | — | Function to run as the new process |
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| `NP_Seglist` | — | Alternative: run from a loaded segment list |
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| `NP_Name` | — | Process name (appears in task list) |
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| `NP_StackSize` | — | Stack size in bytes (default 4096) |
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| `NP_Priority` | — | Task priority (−128 to +127) |
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| `NP_Input` | — | BPTR stdin handle |
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| `NP_Output` | — | BPTR stdout handle |
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| `NP_Error` | — | BPTR stderr handle (OS 3.0+) |
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| `NP_CurrentDir` | — | Lock for current directory |
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| `NP_HomeDir` | — | Lock for PROGDIR: |
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| `NP_CopyVars` | — | Copy parent's local vars to child |
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---
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## SystemTagList — Run a Shell Command
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```c
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/* Execute a command string as if typed in a shell: */
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LONG rc = SystemTagList("dir SYS: ALL", NULL);
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/* rc = return code from the command */
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/* With custom I/O: */
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LONG rc = SystemTagList("list RAM:", (struct TagItem[]){
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{ SYS_Input, Open("NIL:", MODE_OLDFILE) },
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{ SYS_Output, Open("RAM:output.txt", MODE_NEWFILE) },
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{ TAG_DONE, 0 }
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});
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```
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---
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## Execute — Legacy Command Execution
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```c
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/* dos.library LVO −132 */
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BOOL Execute(STRPTR command, BPTR input, BPTR output);
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```
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- `command` — shell command string
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- `input` — BPTR to additional input (0 = none)
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- `output` — BPTR to output handle (0 = current)
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---
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## WaitForChild / Process Exit
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Child processes are independent tasks. To synchronize:
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1. Use a shared `MsgPort` — child sends a death message
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2. Check `pr_Result2` after the child task exits
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3. Use `SYS_Asynch` tag with `SystemTagList` for fire-and-forget
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---
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## References
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- NDK39: `dos/dostags.h`, `dos/dosextens.h`
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- ADCD 2.1: `CreateNewProc`, `SystemTagList`, `Execute`
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- [tasks_processes.md](../06_exec_os/tasks_processes.md) — Task/Process structures
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