Explanation
In Bash, inserting 1>&2 after a command redirects standard output to standard error. This means that the output of the command that normally goes to the standard output stream (file descriptor 1) will be sent to the standard error stream (file descriptor 2) instead. This can be useful if we want to capture or discard both the normal output and the error output of a command. For example, if we want to run a command and send both its output and error to /dev/null (a special device that discards any data written to it), we can use:
command > /dev/null 1>&2
This will redirect the standard output of command to /dev/null, and then redirect the standard error of command to the same place as the standard output, which is /dev/null. The other options are not correct because:
* A. standard error to standard input: This is not possible, because standard input is a read-only stream, and we cannot redirect output to it.
* B. standard input to standard error: This is not what 1>&2 does, because 1 refers to standard output, not standard input. To redirect standard input to standard error, we would need to use 0>&2, where 0 refers to standard input.
* D. standard error to standard output: This is not what 1>&2 does, because it would require the opposite order of file descriptors: 2>&1. This would redirect standard error to standard output, not the other way around.
* E. standard output to standard input: This is not possible, for the same reason as option A. References:
* Bash redirections cheat sheet
* How to redirect stderr to a file - Linuxize