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COM_ERR(3)		   Library Functions Manual		    COM_ERR(3)

       com_err - common	error display routine

	#include <et/com_err.h>

       void com_err (whoami, code, format, ...);
	    const char *whoami;
	    long code;
	    const char *format;

       proc = set_com_err_hook (proc);
       void (* proc ) (const char *, long, const char *, va_list);

       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)) composed	of the whoami string, which should specify the
       program name or some subportion of a program, followed by an error mes-
       sage generated from the code value (derived from	compile_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	procedure which	sends the for-
       matted  text  to	 error output.	Thus the error messages	from a program
       can all easily be diverted to another form of diagnostic	logging,  such
       as  syslog(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  in-

       compile_et (1), syslog (3).

       Ken Raeburn, "A Common Error Description	Library	for UNIX".

SIPB				  22 Nov 1988			    COM_ERR(3)


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