| Input Files

| GNU Assembler Input and Output | Next

We use the phrase source program, abbreviated source, to describe the program input to one run of `as`. The program may be in one or more files; how the source is partitioned into files doesn't change the meaning of the source.
The source program is a concatenation of the text in all the files, in the order specified.
Each time you run `as` it assembles exactly one source program. The source program is made up of one or more files. (The standard input is also a file.)
You give `as` a command line that has zero or more input file names. The input files are read (from left file name to right). A command line argument (in any position) that has no special meaning is taken to be an input file name.
If you give `as` no file names it attempts to read one input file from the `as` standard input, which is normally your terminal. You may have to type `Ctrl-D` to tell `as` there is no more program to assemble.
Use `--` if you need to explicitly name the standard input file in your command line.
If the source is empty, `as` produces a small, empty object file.

- Assembler File Names and Line Numbers