projects / unix-history / blame
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1 | .\" Copyright (c) 1980 Regents of the University of California. |
| 2 | .\" All rights reserved. The Berkeley software License Agreement | |
| 3 | .\" specifies the terms and conditions for redistribution. | |
| 4 | .\" | |
| cdd5eb15 | 5 | .\" @(#)syscall.2 6.2 (Berkeley) %G% |
| 695ad0b4 | 6 | .\" |
| f9effee3 | 7 | .TH SYSCALL 2 "" |
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8 | .UC 4 |
| 9 | .SH NAME | |
| 10 | syscall \- indirect system call | |
| 11 | .SH SYNOPSIS | |
| 12 | .nf | |
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13 | .ft B |
| 14 | #include <syscall.h> | |
| 15 | .PP | |
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16 | .BR "syscall(number, arg, ...)" \ \ (VAX-11) |
| 17 | .fi | |
| 18 | .SH DESCRIPTION | |
| 19 | .I Syscall | |
| 20 | performs the system call whose assembly language | |
| 21 | interface has the specified | |
| 22 | .I number, | |
| 23 | register arguments | |
| 24 | .I r0 | |
| 25 | and | |
| 26 | .I r1 | |
| 92a92bd0 | 27 | and further arguments |
| 695ad0b4 | 28 | .IR arg . |
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29 | Symbolic constants for system calls can be found in the header file |
| 30 | .I <syscall.h>. | |
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31 | .PP |
| 32 | The r0 value of the system call is returned. | |
| 33 | .SH DIAGNOSTICS | |
| 34 | When the C-bit is set, | |
| 35 | .I syscall | |
| 36 | returns \-1 and sets the | |
| 37 | external variable | |
| 38 | .I errno | |
| 39 | (see | |
| 40 | .IR intro (2)). | |
| 41 | .SH BUGS | |
| 42 | There is no way to simulate system calls | |
| 43 | such as | |
| 44 | .IR pipe (2), | |
| 45 | which return values in register r1. |