If you want to concatenate the contents of “file1” and “file2” using the “cat” command and then pass the output to another command, and finally redirect the output of that command to a file, you can use the following syntax:
cat file1 file2 .. | command > file1_out.txt
or if you want to append the output to an existing file:
cat file1 file2 .. | command >> file1_out.txt
In the above examples, “file1_out.txt” is the name of the file where the output of the “command” will be redirected.
Please replace “file1_out.txt” with the desired filename, and modify “command” to the actual command you intend to use.