COM_ERR(3)						     Library Functions Manual							COM_ERR(3)

NAME

       com_err - common error display routine

SYNOPSIS

	#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 ();

DESCRIPTION

       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 message 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 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 syslog(3).  Reset_com_err_hook may be used to restore the behav-
       ior of com_err to its default form.  Both procedures return the previous ``hook'' value.  These ``hook'' procedures must have the  declara-
       tion 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.

SEE ALSO

       compile_et(1), syslog(3).

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

SIPB
								    22 Nov 1988 							COM_ERR(3)