NAME¶
com_err - common error display routine
SYNOPSIS¶
#include <et/com_err.h>
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 ();
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
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.
SEE ALSO¶
compile_et (1), syslog (3).
Ken Raeburn, "A Common Error Description Library for UNIX".