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enosys - Man Page

utility make syscalls fail with ENOSYS


enosys [--syscall|-s syscall] command


enosys is a simple command to execute a child process for which certain syscalls fail with errno ENOSYS.

It can be used to test the behavior of applications in the face of missing syscalls as would happen when running on old kernels.


-s,  --syscall

Syscall to block. Can be specified multiple times.

-i,  --ioctl

Ioctl to block. Can be specified multiple times.

-l,  --list

List syscalls known to enosys.

-m,  --list-ioctl

List ioctls known to enosys.

-h,  --help

Display help text and exit.

-V,  --version

Print version and exit.

Exit Status

enosys exits with the status code of the executed process. The following values have special meanings:

  1. internal error
  2. system does not provide the necessary functionality


Thomas Weißschuh

See Also


Reporting Bugs

For bug reports, use the issue tracker at https://github.com/util-linux/util-linux/issues.


The enosys command is part of the util-linux package which can be downloaded from Linux Kernel Archive.


2024-07-04 util-linux 2.40.2