Exam LX0-103 topic 3 question 49 discussion

Here's why: The command sed -e "s/a/b/" /tmp/file is used to replace all occurrences of the character a with the character b in the file /tmp/file. The > symbol is used for redirection to write the output to a file, in this case, to overwrite the original file /tmp/file. When the shell processes the command, it first opens the file /tmp/file for writing, and then executes the sed command. Since the output file and the input file are the same (/tmp/file), the shell will overwrite the contents of the file before the sed command can read it. As a result, the sed command will not find any occurrences of the character a in the input file, and will output nothing to the output file. Therefore, the file /tmp/file will end up being empty after the command completes.