[ILoveAztecChick]

I'm writing a shell program for a CS class which needs to implement output redirection by messing around with the file descriptor table like this:

fid = open("output", O_CREAT|O_WRONLY);
close(1); //stdout
dup(fid);
close(fid);

For some reason this will create the file and not write anything to it, but if I execute the program using sudo it functions correctly. Is this some screwy thing having to do with UNIX and permissions or is there something wrong with the program itself?

[PBG4 User]

Sounds like the directory you're trying to write the output file to requires higher permissions than the normal user can provide, hence it working when you use sudo.

Try getting the program to write into your home directory without using sudo.

[ILoveAztecChick]

Thanks for the suggestion. That actually wasn't it though. The call to open() takes an additional parameter that specifies the permissions of the created file. Without it my program was creating files without read/write/execute permissions, so only the superuser could access them.

[PBG4 User]

Oops! Oh well at least you figured it out which is the most important part!