Which command is used to concatenate two different files?

The command used to concatenate two different files is 'cat'. This command reads data from files and outputs it to the standard output (typically the terminal). It can take multiple file names as arguments and display their combined content sequentially. For example, executing cat file1.txt file2.txt will display the contents of file1.txt followed immediately by the contents of file2.txt.

While options like 'join', 'merge', and 'combine' suggest operations on files, they serve different purposes. The 'join' command is specifically for merging lines of two files based on a common field, rather than simply concatenating them. There isn't a standard command called 'merge' or 'combine' in Linux for concatenation. Thus, 'cat' remains the appropriate choice for this task.