What does errno 89 (ENOSYS) in Solaris mean?

ENOSYS

Missing or inapplicable operation

ENOSYS is Solaris errno 89 (Unsupported file system operation). Solaris reports that the requested operation is not applicable or not implemented in this context.

Identify the exact system call, command, or optional facility that returned the value and the Solaris release on which it ran. A fallback is appropriate only when the interface documents one; repeated calls cannot implement a missing operation.

What to check

• Check whether the syscall, filesystem operation, or compatibility interface exists on the target Solaris version.
• Use capability detection and a deliberate fallback path.
• Do not retry unless the environment or mounted filesystem changes.

References

• Oracle Solaris intro(2): error numbers
• illumos errno.h definitions
• POSIX errno.h