ls -l sdfsdf bug1.sh
ls -l sdfsdf bug1.sh 2> /dev/null
ls -l sdfsdf bug1.sh 2>&-
## ls: cannot access 'sdfsdf': No such file or directory
## -rwxrwxr-x 1 chau chau 134 Oct 6 15:58 bug1.sh
## -rwxrwxr-x 1 chau chau 134 Oct 6 15:58 bug1.sh
## -rwxrwxr-x 1 chau chau 134 Oct 6 15:58 bug1.sh
ls -l sdfsdf bug1.sh < /dev/null
ls -l sdfsdf bug1.sh <&-
## ls: cannot access 'sdfsdf': No such file or directory
## -rwxrwxr-x 1 chau chau 134 Oct 6 15:58 bug1.sh
## ls: cannot access 'sdfsdf': No such file or directory
## -rwxrwxr-x 1 chau chau 134 Oct 6 15:58 bug1.sh