What's the difference between ">&1" and ">/proc/self/fd/1" redirection?

I'm working on some script that being run by rc.local at startup, and I noticed that output redirection works quite strange. If I write something like echo "foo" >&1, it ends up in syslog, and all is okay. But when I write echo "foo" >>/dev/stdout, or echo "foo" >>/proc/self/fd/1, I got an error saying that there is no such device or address. Further investigation revealed that /proc/self/fd/1 was in fact a socket. Including ls -l /proc/self/fd in rc.local prints the following: lr-x------. 1 root root 64 Jul 14 05:28 0 -> /dev/null lrwx------. 1 root root 64 Jul 14 05:28 1 -> socket: lrwx------. 1 root root 64 Jul 14 05:28 2 -> socket: lr-x------. 1 root root 64 Jul 14 05:28 255 -> /etc/rc.d/rc.local ---------- The described behaviour can be easily reproduced with nc. First, find out which file descriptor binds to socket. You can do it by issuing nc -l -p 25566 -c "ls -l /proc/self/fd" in first terminal and then telnet localhost 25566 in other terminal. In my case it was 5-th descriptor. Okay. Then, to reproduce the issue, in first terminal: nc -l -p 25566 -c "echo 'hello' >&5" in second terminal: telnet localhost 25566 You shall see "hello" in second terminal output between telnet messages about connection being established and closed. Now the case with file descriptor pseudo-file from /proc: first terminal: nc -l -p 25566 -c "echo 'hello' >/proc/self/fd/5" second terminal: telnet localhost 25566 Now second terminal just contains telnet messages about connection established and immediately closed, and first terminal shows an error: sh: /proc/self/fd/5: No such device or address. **Edit:** OS is Fedora 23 i686 server ---------- So, the question. What's the difference between >&1 and >/proc/self/fd/1 ? And is there some universal and reliable way to redirect output to some file, which corresponds exactly to current standard output? Thank you. ---------- **Edit 2:** For clarity, exact input/output for Fedora 23 i686 for above case: Terminal 1 | Terminal 2 $ nc -l -p 25566 -c 'ls -go /proc/self/fd' | | $ telnet localhost 25566 | Trying ::1... | Connected to localhost. | Escape character is '^]'. | total 0 | lr-x------ 1 64 Jul 14 08:56 0 -> pipe: | l-wx------ 1 64 Jul 14 08:56 1 -> pipe: | lrwx------ 1 64 Jul 14 08:56 2 -> /dev/tty2 | lr-x------ 1 64 Jul 14 08:56 3 -> pipe: | lr-x------ 1 64 Jul 14 08:56 4 -> /proc/1285/fd | lrwx------ 1 64 Jul 14 08:56 5 -> socket: | l-wx------ 1 64 Jul 14 08:56 7 -> /pipe: | Connection closed by foreign host. $ nc -l -p 25566 -c "echo 'hi' >&5" | | $ telnet localhost 25566 | Trying ::1... | Connected to localhost. | Escape character is '^]'. | hi | Connection closed by foreign host. $ nc -l -p 25566 -c "echo 'hi' >/proc/self/fd/5" | | $ telnet localhost 25566 | Trying ::1... | Connected to localhost. sh: /proc/self/fd/5: No such device or address | Escape character is '^]'. | Connection closed by foreign host. $ | $