com_err - common error display routine
void com_err (whoami, code, format, ...);
const char *whoami;
const char *format;
proc = set_com_err_hook (proc);
void (* proc ) (const char *, long, const char *,
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 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.
compile_et (1), syslog (3).
Ken Raeburn, "A Common Error Description Library for
SIPB 22 Nov 1988 2 [ Back ]