## warn

#### OS/161 Reference Manual

### Name

warn, warnx, vwarn, vwarnx - print warning messages

### Library

Standard C Library (libc, -lc)

### Synopsis

`#include <err.h>`
`void`
`warn(const char *`format`, ...);`
`void`
`warnx(const char *`format`, ...);`
`void`
`vwarn(const char *`format`, va_list);`
`void`
`vwarnx(const char *`format`, va_list);`

### Description

The `warn`, `warnx`, `vwarn`, and `vwarnx` functions print warning messages to the standard error stream.

`warnx` prints the name of the program, a colon, the text generated by passing format and subsequent args through printf, and a newline.

`warn` prints 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.

`vwarnx` and `vwarn` are the same as `warnx` and `warn` 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.

### See Also

err