| [23095] | 1 | .\" Copyright (c) 1988 Massachusetts Institute of Technology, |
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| 2 | .\" Student Information Processing Board. All rights reserved. |
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| 3 | .\" |
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| [23740] | 4 | .\" $Header: /afs/athena.mit.edu/astaff/project/moiradev/repository/moira/util/et/com_err.3,v 1.2 1998-02-05 22:13:00 danw Exp $ |
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| [23095] | 5 | .\" |
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| 6 | .TH COM_ERR 3 "22 Nov 1988" SIPB |
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| 7 | .SH NAME |
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| 8 | com_err \- common error display routine |
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| 9 | .SH SYNOPSIS |
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| 10 | .nf |
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| 11 | #include <com_err.h> |
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| 12 | .PP |
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| 13 | void com_err (whoami, code, format, ...); |
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| 14 | const char *whoami; |
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| 15 | long code; |
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| 16 | const char *format; |
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| 17 | .PP |
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| 18 | proc = set_com_err_hook (proc); |
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| 19 | .fi |
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| 20 | void (* |
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| 21 | .I proc |
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| 22 | ) (const char *, long, const char *, va_list); |
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| 23 | .nf |
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| 24 | .PP |
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| 25 | proc = reset_com_err_hook (); |
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| 26 | .PP |
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| 27 | void initialize_XXXX_error_table (); |
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| 28 | .fi |
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| 29 | .SH DESCRIPTION |
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| 30 | .I Com_err |
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| 31 | displays an error message on the standard error stream |
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| 32 | .I stderr |
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| 33 | (see |
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| 34 | .IR stdio (3S)) |
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| 35 | composed of the |
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| 36 | .I whoami |
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| 37 | string, which should specify the program name or some subportion of |
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| 38 | a program, followed by an error message generated from the |
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| 39 | .I code |
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| 40 | value (derived from |
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| 41 | .IR compile_et (1)), |
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| 42 | and a string produced using the |
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| 43 | .I format |
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| 44 | string and any following arguments, in the same style as |
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| 45 | .IR fprintf (3). |
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| 46 | |
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| 47 | The behavior of |
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| 48 | .I com_err |
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| 49 | can be modified using |
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| 50 | .I set_com_err_hook; |
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| 51 | this defines a procedure which is called with the arguments passed to |
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| 52 | .I com_err, |
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| 53 | instead of the default internal procedure which sends the formatted |
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| 54 | text to error output. Thus the error messages from a program can all |
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| 55 | easily be diverted to another form of diagnostic logging, such as |
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| 56 | .IR syslog (3). |
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| 57 | .I Reset_com_err_hook |
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| 58 | may be used to restore the behavior of |
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| 59 | .I com_err |
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| 60 | to its default form. Both procedures return the previous ``hook'' |
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| 61 | value. These ``hook'' procedures must have the declaration given for |
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| 62 | .I proc |
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| 63 | above in the synopsis. |
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| 64 | |
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| 65 | The |
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| 66 | .I initialize_XXXX_error_table |
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| 67 | routine is generated mechanically by |
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| 68 | .IR compile_et (1) |
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| 69 | from a source file containing names and associated strings. Each |
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| 70 | table has a name of up to four characters, which is used in place of |
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| 71 | the |
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| 72 | .B XXXX |
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| 73 | in the name of the routine. These routines should be called before |
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| 74 | any of the corresponding error codes are used, so that the |
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| 75 | .I com_err |
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| 76 | library will recognize error codes from these tables when they are |
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| 77 | used. |
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| 78 | |
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| 79 | The |
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| 80 | .B com_err.h |
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| 81 | header file should be included in any source file that uses routines |
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| 82 | from the |
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| 83 | .I com_err |
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| 84 | library; executable files must be linked using |
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| 85 | .I ``-lcom_err'' |
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| 86 | in order to cause the |
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| 87 | .I com_err |
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| 88 | library to be included. |
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| 89 | |
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| 90 | .\" .IR for manual entries |
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| 91 | .\" .PP for paragraph breaks |
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| 92 | |
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| 93 | .SH "SEE ALSO" |
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| 94 | compile_et (1), syslog (3). |
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| 95 | |
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| 96 | Ken Raeburn, "A Common Error Description Library for UNIX". |
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