ENOSYS(1) User Commands ENOSYS(1)
NAME
enosys - utility to make syscalls fail with ENOSYS
SYNOPSIS
enosys [--syscall|-s syscall] command
DESCRIPTION
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.
OPTIONS
-s, --syscall
Syscall to block with ENOSYS. Can be specified multiple times. An
alternative error number or name can be specified with a colon.
-i, --ioctl
Ioctl to block with ENOTTY. Can be specified multiple times. An
alternative error number or name can be specified with a colon.
-l, --list
List syscalls known to enosys.
-m, --list-ioctl
List ioctls known to enosys.
-d, --dump[=file]
Dump seccomp bytecode filter to standard output.
The dump can for example be used by setpriv --seccomp-filter.
-h, --help
Display help text and exit.
-V, --version
Display version and exit.
EXAMPLES
# fail syscall "fallocate" with ENOSYS
enosys -s fallocate ...
# fail syscall "fallocate" with ENOMEM
enosys -s fallocate:ENOMEM ...
# fail syscall "fallocate" with value 12/ENOMEM
enosys -s fallocate:12 ...
# fail ioctl FIOCLEX with ENOTTY
enosys -i FIOCLEX ...
# fail ioctl FIOCLEX with ENOMEM
enosys -i FIOCLEX:ENOMEM ...
# fail ioctl FIOCLEX with value 12/ENOMEM
enosys -i FIOCLEX:12 ...
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
AUTHORS
Thomas Weißschuh <thomas@t-8ch.de>
SEE ALSO
syscall(2)
REPORTING BUGS
For bug reports, use the issue tracker
<https://github.com/util-linux/util-linux/issues>.
AVAILABILITY
The enosys command is part of the util-linux package which can be
downloaded from Linux Kernel Archive
<https://www.kernel.org/pub/linux/utils/util-linux/>.
util-linux 2.41 2025-02-26 ENOSYS(1)
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