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QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
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C Library Reference
U
umount()
Unmount a filesystem

QNX Momentics IDE User's Guide
This User's Guide describes version 8.0 of the Integrated Development Environment (IDE) that's part of the QNX Tool Suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
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      - ualarm()
        Schedule an alarm
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        Set the file-mode creation mask for the process
      - umount()
        Unmount a filesystem
      - UNALIGNED_PUT16()
        Write a misaligned 16-bit value safely
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        Write a misaligned 32-bit value safely
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        Write a misaligned 64-bit value safely
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        Access a misaligned 16-bit value safely
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        Access a misaligned 32-bit value safely
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        Get information about the operating system
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        Unregister an I/O control handler
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        Remove a link to a file
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        Remove a link to a file at a given location
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        Unlock a pseudo-terminal master/slave pair
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        Remove an environment variable
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Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation, explains how to obtain technical support, and provides some information about licensing.

umount()

QNX SDP8.0C Library ReferenceAPIDeveloper

Unmount a filesystem

Synopsis:

#include <sys/mount.h>

int umount( const char* dir, 
            int flags);

Arguments:

dir

The filesystem that you want to unmount.

flags

Flags that control the operation. Currently, the only valid value for flags is:

_MOUNT_FORCE — force an unmount to occur.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The umount() function sends a request to the server to unmount the path described by dir.

Returns:

-1 on failure (errno is set).

Classification:

QNX OS


Safety:
Cancellation point	Yes
Signal handler	No
Thread	Yes

Page updated: August 11, 2025