perror---print an error message on standard error#include <stdio.h> void perror(char *prefix); void _perror_r(void *reent, char *prefix);Description
perror to print (on standard error) an error message
corresponding to the current value of the global variable errno.
Unless you use NULL as the value of the argument prefix, the
error message will begin with the string at prefix, followed by a
colon and a space (: ). The remainder of the error message is one
of the strings described for strerror.
The alternate function _perror_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
perror returns no result.
Portability
ANSI C requires perror, but the strings issued vary from one
implementation to another.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.