---
name: "fmtmsg.h"
section: "0p"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/fmtmsg.h"
---

# fmtmsg.h(0p)

message display structures

## PROLOG

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

## NAME

fmtmsg.h — message display structures

## SYNOPSIS

```
#include <fmtmsg.h>
```

## DESCRIPTION

The *\<fmtmsg.h\>* header shall define the following symbolic constants:

- MM\_HARD

  Source of the condition is hardware.

- MM\_SOFT

  Source of the condition is software.

- MM\_FIRM

  Source of the condition is firmware.

- MM\_APPL

  Condition detected by application.

- MM\_UTIL

  Condition detected by utility.

- MM\_OPSYS

  Condition detected by operating system.

- MM\_RECOVER

  Recoverable error.

- MM\_NRECOV

  Non-recoverable error.

- MM\_HALT

  Error causing application to halt.

- MM\_ERROR

  Application has encountered a non-fatal fault.

- MM\_WARNING

  Application has detected unusual non-error condition.

- MM\_INFO

  Informative message.

- MM\_NOSEV

  No severity level provided for the message.

- MM\_PRINT

  Display message on standard error.

- MM\_CONSOLE

  Display message on system console.

The table below indicates the null values and identifiers for *fmtmsg*() arguments. The *\<fmtmsg.h\>* header shall define the symbolic constants in the **Identifier** column, which shall have the type indicated in the **Type** column:

| | | | |
| --- | --- | --- | --- |
| **Argument** | **Type** | **Null-Value** | **Identifier** |
| *label* | **char \*** | (**char**\*)0 | MM\_NULLLBL |
| *severity* | **int** | 0 | MM\_NULLSEV |
| *class* | **long** | **0L** | MM\_NULLMC |
| *text* | **char \*** | (**char**\*)0 | MM\_NULLTXT |
| *action* | **char \*** | (**char**\*)0 | MM\_NULLACT |
| *tag* | **char \*** | (**char**\*)0 | MM\_NULLTAG |

The *\<fmtmsg.h\>* header shall also define the following symbolic constants for use as return values for *fmtmsg*():

- MM\_OK

  The function succeeded.

- MM\_NOTOK

  The function failed completely.

- MM\_NOMSG

  The function was unable to generate a message on standard error, but otherwise succeeded.

- MM\_NOCON

  The function was unable to generate a console message, but otherwise succeeded.

The following shall be declared as a function and may also be defined as a macro. A function prototype shall be provided.

```
int fmtmsg(long, const char *, int,
    const char *, const char *, const char *);
```

*The following sections are informative.*

## APPLICATION USAGE

None.

## RATIONALE

None.

## FUTURE DIRECTIONS

None.

## SEE ALSO

The System Interfaces volume of POSIX.1‐2017, *fmtmsg()*

## COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting\_bugs.html .