On 12 May 2015 at 12:56, Daniel Bastos <[email protected]> wrote: > % cp /fd/1 /fd/0 > cp: can't open /fd/1: '/fd/1' inappropriate use of fd > > I can't open it for reading, but I could open it for writing. Why can't I > open it for reading? >
The file open on file descriptor 1 wasn't itself opened for reading, only writing. Check with ls -l /fd/1: h% ls -l /fd/0 /fd/1 --r-------- d 0 bootes bootes 0 Jul 2 2014 /fd/0 ---w------- d 0 bootes bootes 0 Jul 2 2014 /fd/1 The "bootes" is wrong, though: the driver should use up->user (not hostowner, or even the owner of the underlying file). You'll notice that someone else had /fd/1 with both r and w, in which case cp /fd/1 /fd/0 would instead have complained about /fd/0 since /fd/1 could be opened, but /fd/0 can't be written.
