GNU as - the portable GNU assembler.
as [-a[dhlns][=file]] [-D] [--defsym SYM=VAL] [-f]
[--gstabs] [-I path] [-K] [-L] [-M | --mri] [-o objfile]
[-R] [--traditional-format] [-v] [-w] [-- | files...]
[-ACA|-ACA_A|-ACB|-ACC|-AKA|-AKB|-AKC|-AMC] [-b] [-no-
GNU as is really a family of assemblers. If you use (or
have used) the GNU assembler on one architecture, you
should find a fairly similar environment when you use it
on another architecture. Each version has much in common
with the others, including object file formats, most
assembler directives (often called pseudo-ops) and assembler
For information on the syntax and pseudo-ops used by GNU
as, see `as' entry in info (or the manual Using as: The
as is primarily intended to assemble the output of the GNU
C compiler gcc for use by the linker ld. Nevertheless,
we've tried to make as assemble correctly everything that
the native assembler would. This doesn't mean as always
uses the same syntax as another assembler for the same
architecture; for example, we know of several incompatible
versions of 680x0 assembly language syntax.
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.)
If as is given 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 ctl-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
as may write warnings and error messages to the standard
error file (usually your terminal). This should not happen
when as is run automatically by a compiler. Warnings
report an assumption made so that as could keep assembling
a flawed program; errors report a grave problem that stops
-a Turn on assembly listings. There are various suboptions.
d omits debugging directives. h includes
the high level source code; this is only available
if the source file can be found, and the code was
compiled with -g. l includes an assembly listing.
n omits forms processing. s includes a symbol
listing. = file sets the listing file name; this
must be the last suboption. The default suboptions
-D This option is accepted only for script compatibility
with calls to other assemblers; it has no
effect on as.
Define the symbol SYM to be VALUE before assembling
the input file. VALUE must be an integer constant.
As in C, a leading 0x indicates a hexadecimal
value, and a leading 0 indicates an octal value.
-f ``fast''--skip preprocessing (assume source is compiler
Add path to the search list for .include directives.
Generate stabs debugging information for each
assembler line. This may help debugging assembler
code, if the debugger can handle it.
-K Issue warnings when difference tables altered for
-L Keep (in symbol table) local symbols, starting with
Assemble in MRI compatibility mode.
Name the object-file output from as
-R Fold data section into text section
Use same format as native assembler, when possible.
-v Announce as version
Suppress warning messages.
Consider warnings to be fatal.
--warn Just warn on warnings.
-- | files...
Source files to assemble, or standard input (--)
-Avar (When configured for Intel 960.) Specify which
variant of the 960 architecture is the target.
-b (When configured for Intel 960.) Add code to collect
statistics about branches taken.
(When configured for Intel 960.) Do not alter
compare-and-branch instructions for long displacements;
error if necessary.
-l (When configured for Motorola 68000).
Shorten references to undefined symbols, to one
word instead of two.
(When configured for Motorola 68000).
Specify what processor in the 68000 family is the
target (default 68020)
Options may be in any order, and may be before, after, or
between file names. The order of file names is significant.
`--' (two hyphens) by itself names the standard input file
explicitly, as one of the files for as to assemble.
Except for `--' any command line argument that begins with
a hyphen (`-') is an option. Each option changes the
behavior of as. No option changes the way another option
works. An option is a `-' followed by one or more letters;
the case of the letter is important. All options
The `-o' option expects exactly one file name to follow.
The file name may either immediately follow the option's
letter (compatible with older assemblers) or it may be the
next command argument (GNU standard).
These two command lines are equivalent:
as -o my-object-file.o mumble.s
as -omy-object-file.o mumble.s
`as' entry in info; Using as: The GNU Assembler; gcc(1),
Copyright (c) 1991, 1992, 2000 Free Software Foundation,
This document is distributed under the terms of the GNU
Free Documentation License, version 1.1. That license is
described in the sources for this manual page, but it is
not displayed here in order to make this manual more consise.
Copies of this license can also be obtained from:
Free Software Foundation 29 March 1996 as(1)
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