How can I get the architecture of a '.a' file?

linux elf

31,293

Solution 1

You can also skip the ar command and use readelf, via something like:

readelf -h <archive>.a | grep 'Class\|File\|Machine'

[00:32:15] /usr/lib $ readelf -h libxslt.a | grep 'Class\|File\|Machine'
File: libxslt.a(attrvt.o)
  Class:                             ELF32
  Machine:                           Intel 80386
File: libxslt.a(xslt.o)
  Class:                             ELF32
  Machine:                           Intel 80386
... #Trimmed this, it goes on a bit
File: libxslt.a(transform.o)
  Class:                             ELF32
  Machine:                           Intel 80386
File: libxslt.a(security.o)
  Class:                             ELF32
  Machine:                           Intel 80386
[00:32:24] /usr/lib $

In case it's relevant, here's the other information that you can get from readelf -h. I just trimmed the above with grep, obviously:

File: libxslt.a(security.o)
ELF Header:
  Magic:   7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 
  Class:                             ELF32
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              REL (Relocatable file)
  Machine:                           Intel 80386
  Version:                           0x1
  Entry point address:               0x0
  Start of program headers:          0 (bytes into file)
  Start of section headers:          2548 (bytes into file)
  Flags:                             0x0
  Size of this header:               52 (bytes)
  Size of program headers:           0 (bytes)
  Number of program headers:         0
  Size of section headers:           40 (bytes)
  Number of section headers:         16
  Section header string table index: 13

That output is for one of the object files in libxslt.a, but it gives the same information for each file.

Solution 2

Use

lipo -info libExample.a

It will Who the architecture it build for. Other functions like otool or file doesn't give the exact answer and sometimes it to verbose to get the correct information.

Solution 3

objdump is another option:

objdump -a file.a|grep 'file format'

Solution 4

http://linux.die.net/man/1/ar

extract the object files from the archive and inspect them with file(1), nm(1), etc.

View more solutions

31,293

Author by

Mike

Updated on February 20, 2020

Comments

Mike over 4 years

I have a .a file from which I want to get architecture information. Running file myFile.a results in file.a: current ar archive. How can I get more information on what architecture the file contains?
Mike almost 14 years

Is there any way to get architecture information without extracting its contents(at least without leaving any residue behind)?
cHao almost 14 years

Recommend adding Machine to the list there. That'll include info on the specific CPU the object files are made for, rather than just whether it's 32 or 64 bit or whatever.
Matthew Flaschen almost 14 years

@jer, actually, you can do it with either readelf or objdump.
eldarerathis almost 14 years

@cHao: Yeah, I just thought of that, too. I'm doing another edit (and I added the entire output of readelf -h).
Mike almost 14 years

Thanks! This is exactly what I was looking for.
jer almost 14 years

@Matthew, Sorry, my mind was in OSX/iOS mode i'd been answering those questions all night, and didn't read the tag closely enough. Yeah, you are correct. Neither of those tools exist in osx's dev tools (one doesn't make sense on that platform anyway).
MetalGodwin over 8 years

lipo seems to be OS X specific.
Mahler almost 5 years

Can not get architecture information (e.g. arm, x86, etc.) by this solution.