err, errx, verr, verrx - print error messages
Standard C Library (libc, -lc)
err(int exitcode, const char *format, ...);
errx(int exitcode, const char *format, ...);
verr(int exitcode, const char *format, va_list);
verrx(int exitcode, const char *format, va_list);
The err, errx, verr, and verrx functions print error messages to the standard error stream.
errx prints the name of the program, a colon, the text generated by passing format and subsequent args through printf, and a newline. Then, exit is called and passed the supplied exitcode.
err does the same thing, except that a colon and the error string for the current error (obtained by calling strerror on errno) are printed prior to the newline.
verrx and verr are the same as errx and err respectively, except that the additional arguments for printf are taken to have been already packaged up in a va_list by use of the stdarg facility.