Standard output redirection and output redirection

Standard output redirection and output redirection

Use the ls command to demonstrate:

Note1: when you enter the correct ls command, the output is stored in the abc file in overwrite mode.

Note2: When lsss (incorrect ls) is input, the wrong command output is not stored in abc in overwrite mode, so it is an empty file.

However, there is a bug in this method, that is, to determine whether your input command is correct, Your output redirection makes sense. So this method is not good.

Note1: If the ls output is correct or incorrect, it is saved to abc.