<html lang="en">
<head>
<title>Input Files - Using as</title>
<meta http-equiv="Content-Type" content="text/html">
<meta name="description" content="Using as">
<meta name="generator" content="makeinfo 4.13">
<link title="Top" rel="start" href="index.html#Top">
<link rel="up" href="Overview.html#Overview" title="Overview">
<link rel="prev" href="Command-Line.html#Command-Line" title="Command Line">
<link rel="next" href="Object.html#Object" title="Object">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
<!--
This file documents the GNU Assembler "as".

Copyright (C) 1991-2019 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, with no Front-Cover Texts, and with no
Back-Cover Texts.  A copy of the license is included in the
section entitled ``GNU Free Documentation License''.

-->
<meta http-equiv="Content-Style-Type" content="text/css">
<style type="text/css"><!--
  pre.display { font-family:inherit }
  pre.format  { font-family:inherit }
  pre.smalldisplay { font-family:inherit; font-size:smaller }
  pre.smallformat  { font-family:inherit; font-size:smaller }
  pre.smallexample { font-size:smaller }
  pre.smalllisp    { font-size:smaller }
  span.sc    { font-variant:small-caps }
  span.roman { font-family:serif; font-weight:normal; } 
  span.sansserif { font-family:sans-serif; font-weight:normal; } 
--></style>
</head>
<body>
<div class="node">
<a name="Input-Files"></a>
<p>
Next:&nbsp;<a rel="next" accesskey="n" href="Object.html#Object">Object</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="Command-Line.html#Command-Line">Command Line</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="Overview.html#Overview">Overview</a>
<hr>
</div>

<h3 class="section">1.5 Input Files</h3>

<p><a name="index-input-29"></a><a name="index-source-program-30"></a><a name="index-files_002c-input-31"></a>We use the phrase <dfn>source program</dfn>, abbreviated <dfn>source</dfn>, to
describe the program input to one run of <samp><span class="command">as</span></samp>.  The program may
be in one or more files; how the source is partitioned into files
doesn't change the meaning of the source.

<!-- I added "con" prefix to "catenation" just to prove I can overcome my -->
<!-- APL training...   doc@cygnus.com -->
   <p>The source program is a concatenation of the text in all the files, in the
order specified.

<!-- man begin DESCRIPTION -->
   <p>Each time you run <samp><span class="command">as</span></samp> it assembles exactly one source
program.  The source program is made up of one or more files. 
(The standard input is also a file.)

   <p>You give <samp><span class="command">as</span></samp> 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.

   <p>If you give <samp><span class="command">as</span></samp> no file names it attempts to read one input file
from the <samp><span class="command">as</span></samp> standard input, which is normally your terminal.  You
may have to type &lt;ctl-D&gt; to tell <samp><span class="command">as</span></samp> there is no more program
to assemble.

   <p>Use &lsquo;<samp><span class="samp">--</span></samp>&rsquo; if you need to explicitly name the standard input file
in your command line.

   <p>If the source is empty, <samp><span class="command">as</span></samp> produces a small, empty object
file.

<!-- man end -->
<h4 class="subheading">Filenames and Line-numbers</h4>

<p><a name="index-input-file-linenumbers-32"></a><a name="index-line-numbers_002c-in-input-files-33"></a>There are two ways of locating a line in the input file (or files) and
either may be used in reporting error messages.  One way refers to a line
number in a physical file; the other refers to a line number in a
&ldquo;logical&rdquo; file.  See <a href="Errors.html#Errors">Error and Warning Messages</a>.

   <p><dfn>Physical files</dfn> are those files named in the command line given
to <samp><span class="command">as</span></samp>.

   <p><dfn>Logical files</dfn> are simply names declared explicitly by assembler
directives; they bear no relation to physical files.  Logical file names help
error messages reflect the original source file, when <samp><span class="command">as</span></samp> source
is itself synthesized from other files.  <samp><span class="command">as</span></samp> understands the
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; directives emitted by the <code>gcc</code> preprocessor.  See also
<a href="File.html#File"><code>.file</code></a>.

   </body></html>