Should we reject commands with multiple inputs/outputs ?

[tao-guo]

The results are quite different between zsh and bash:

• multiple outputs

# zsh
➜  rust_cmd_lib git:(master) ✗ echo aaa >/tmp/f1 >/tmp/f2 >/tmp/f3
➜  rust_cmd_lib git:(master) ✗ cat /tmp/f1
aaa
➜  rust_cmd_lib git:(master) ✗ cat /tmp/f2
aaa
➜  rust_cmd_lib git:(master) ✗ cat /tmp/f3
aaa

# bash
➜  rust_cmd_lib git:(master) ✗ bash
~/src/rust/rust_cmd_lib$ echo aaa >/tmp/f4 >/tmp/f5 >/tmp/f6
~/src/rust/rust_cmd_lib$ cat /tmp/f4
~/src/rust/rust_cmd_lib$ cat /tmp/f5
~/src/rust/rust_cmd_lib$ cat /tmp/f6
aaa
~/src/rust/rust_cmd_lib$

• multiple inputs

# zsh
➜  rust_cmd_lib git:(master) ✗ ls | wc -l < README.md
281

# bash
➜  rust_cmd_lib git:(master) ✗ bash
~/src/rust/rust_cmd_lib$ ls | wc -l < README.md 
271

Since rust_cmd_lib can do parsing at compile time, we can actually reject such commands. Just want to know more feedback before making changes to reject such commands.