10-02-2008
Rationale
What is the reason that you want such an implementation?
errno is usually set by the called function when it returns to indicate whether it failed or succeeded.
Exceptions are those functions that don't use errno but may set it unknowingly. In any case it's not advisable to assume anything.
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LEARN ABOUT REDHAT
perror
PERROR(3) Library functions PERROR(3)
NAME
perror - print a system error message
SYNOPSIS
#include <stdio.h>
void perror(const char *s);
#include <errno.h>
const char *sys_errlist[];
int sys_nerr;
DESCRIPTION
The routine perror() produces a message on the standard error output, describing the last error encountered during a call to a system or
library function. First (if s is not NULL and *s is not NUL) the argument string s is printed, followed by a colon and a blank. Then the
message and a new-line.
To be of most use, the argument string should include the name of the function that incurred the error. The error number is taken from the
external variable errno, which is set when errors occur but not cleared when non-erroneous calls are made.
The global error list sys_errlist[] indexed by errno can be used to obtain the error message without the newline. The largest message num-
ber provided in the table is sys_nerr -1. Be careful when directly accessing this list because new error values may not have been added to
sys_errlist[].
When a system call fails, it usually returns -1 and sets the variable errno to a value describing what went wrong. (These values can be
found in <errno.h>.) Many library functions do likewise. The function perror() serves to translate this error code into human-readable
form. Note that errno is undefined after a successful library call: this call may well change this variable, even though it succeeds, for
example because it internally used some other library function that failed. Thus, if a failing call is not immediately followed by a call
to perror, the value of errno should be saved.
CONFORMING TO
ANSI C, BSD 4.3, POSIX, X/OPEN
SEE ALSO
strerror(3)
2001-12-14 PERROR(3)