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