examples/intro/redirection_bash.txt
$ ls -l /bin/bash /bing/other
ls: /bing/other: No such file or directory
-r-xr-xr-x  1 root  wheel  1228240 Oct 29 13:31 /bin/bash


$ ls -l /bin/bash /bing/other > out
ls: /bing/other: No such file or directory


$ ls -l /bin/bash /bing/other 1> out
ls: /bing/other: No such file or directory


$ ls -l /bin/bash /bing/other 2> err
-r-xr-xr-x  1 root  wheel  1228240 Oct 29 13:31 /bin/bash


$ ls -l /bin/bash /bing/other > out  2> err


$ ls -l /bin/bash /bing/other 2> /dev/null
-r-xr-xr-x  1 root  wheel  1228240 Oct 29 13:31 /bin/bash