Hi, i wrote: > > shred: -: invalid file type
to...@tuxteam.de wrote: > Hmm. This looks like a genuine bug: the man page mentions it. Even the help text in https://sources.debian.org/src/coreutils/9.4-3/src/shred.c/ says If FILE is -, shred standard output. The name "-" is recognized in line 1257 and leads to a call of wipefd() in line 958. The error messages there look different from above. So i hop from line 973 to do_wipefd() and find the message in line 845. fd is supposed to be 1 (= stdout). fstat(2) was successful but now this condition snaps: if ((S_ISCHR (st.st_mode) && isatty (fd)) || S_ISFIFO (st.st_mode) || S_ISSOCK (st.st_mode)) The problem seems to be in the S_ISFIFO part. In a little test program fstat() reports about fd==1: st.st_mode= 010600 , S_ISFIFO(st.st_mode)= 1 (st_mode shown in octal as in man 2 fstat.) It looks like the test expects a pipe(2) file descriptor to be classified as S_ISCHR and !isatty(). Without redirection through a pipe, fd 1 has st.st_mode 20620, S_ISCHR, and isatty()==1. The isatty() result is indeed a good reason, not to flood stdout by a zillion random bytes. Does anybody have an old GNU/Linux system where a file descriptor from pipe(2) is classified as character device (S_IFCHR, S_ISCHR) ? Does anybody have an idea why shred would want to exclude fifos ? (What ciould shred do with a non-tty character device that cannot be done with a fifo ?) Have a nice day :) Thomas
