com_err - common error display routine
void (*proc) (const char *, long, const char *, va_list);
void com_err (const char *whoami, long code, const char *format, ...);
proc = set_com_err_hook (proc);
proc = reset_com_err_hook ();
void initialize_XXXX_error_table ();
Com_err displays an error message on the standard error stream stderr (see stdio(3S)) com-
posed of the whoami string, which should specify the program name or some subportion of a
program, followed by an error message generated from the code value (derived from com-
pile_et(1)), and a string produced using the format string and any following arguments, in
the same style as fprintf(3).
The behavior of com_err can be modified using set_com_err_hook; this defines a procedure
which is called with the arguments passed to com_err, instead of the default internal pro-
cedure which sends the formatted text to error output. Thus the error messages from a
program can all easily be diverted to another form of diagnostic logging, such as sys-
log(3). Reset_com_err_hook may be used to restore the behavior of com_err to its default
form. Both procedures return the previous ``hook'' value. These ``hook'' procedures must
have the declaration given for proc above in the synopsis.
The initialize_XXXX_error_table routine is generated mechanically by compile_et(1) from a
source file containing names and associated strings. Each table has a name of up to four
characters, which is used in place of the XXXX in the name of the routine. These routines
should be called before any of the corresponding error codes are used, so that the com_err
library will recognize error codes from these tables when they are used.
The com_err.h header file should be included in any source file that uses routines from
the com_err library; executable files must be linked using ``-lcom_err'' in order to cause
the com_err library to be included.
Ken Raeburn, "A Common Error Description Library for UNIX".
SIPB 22 Nov 1988 COM_ERR(3)