"inappropriate ioctl for device"

Question

I have a Perl script running in an AIX box.

The script tries to open a file from a certain directory and it fails to read the file because file has no read permission, but I get a different error saying inappropriate ioctl for device.

Shouldn't it say something like no read permissions for file or something similar?

What does this inappropriate ioctl for device message mean?

How can I fix it?

EDIT: This is what I found when I did strace.

open("/local/logs/xxx/xxxxServer.log", O_WRONLY|O_CREAT|O_APPEND|O_LARGEFILE, 
    0666) = 4 _llseek(4, 0, [77146], SEEK_END) = 0
ioctl(4, SNDCTL_TMR_TIMEBASE or TCGETS, 0xbffc14f8) = -1 ENOTTY 
    (Inappropriate ioctl for  device)

Answer 1

Most likely it means that the open didn't fail.

When Perl opens a file, it checks whether or not the file is a TTY (so that it can answer the -T $fh filetest operator) by issuing the TCGETS ioctl against it. If the file is a regular file and not a tty, the ioctl fails and sets errno to ENOTTY (string value: "Inappropriate ioctl for device"). As ysth says, the most common reason for seeing an unexpected value in $! is checking it when it's not valid -- that is, anywhere other than immediately after a syscall failed, so testing the result codes of your operations is critically important.

If open actually did return false for you, and you found ENOTTY in $! then I would consider this a small bug (giving a useless value of $!) but I would also be very curious as to how it happened. Code and/or truss output would be nifty.

Answer 2

Odd errors like "inappropriate ioctl for device" are usually a result of checking $! at some point other than just after a system call failed. If you'd show your code, I bet someone would rapidly point out your error.