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LIBXO(3) FreeBSD Library Functions Manual LIBXO(3) NAME xo_err, xo_errc, xo_errx xo_warn, xo_warnx, xo_warn_c, xo_warn_hc - emit errors and warnings in multiple output styles LIBRARY Text, XML, JSON, and HTML Output Emission Library (libxo, -lxo) SYNOPSIS #include <libxo/xo.h> void xo_warn(const char *fmt, ...); void xo_warnx(const char *fmt, ...); void xo_warn_c(int code, const char *fmt, ...); void xo_warn_hc(xo_handle_t *xop, int code, const char *fmt, ...); void xo_err(int eval, const char *fmt, ...); void xo_errc(int eval, int code, const char *fmt, ...); void xo_errx(int eval, const char *fmt, ...); DESCRIPTION Many programs make use of the standard library functions err(3) and warn(3) to generate errors and warnings for the user. libxo wants to pass that information via the current output style, and provides compatible functions to allow this. The fmt argument is one compatible with printf(3) rather than xo_emit(3) to aid in simple conversion. This means these functions make unstructured data. To generate structured data, use the xo_emit_err(3) functions. These functions display the program name, a colon, a formatted message based on the arguments, and then optionally a colon and an error message associated with either errno or the code parameter. EXAMPLE: if (open(filename, O_RDONLY) < 0) xo_err(1, "cannot open file '%s'", filename); SEE ALSO xo_emit(3), xo_emit_err(3), libxo(3) HISTORY The libxo library first appeared in FreeBSD 11.0. AUTHORS