Check glibc version for a particular gcc compiler - c

Question

I have two gcc compilers installed on my system, one is gcc 4.1.2 (default) and the other is gcc 4.4.4. How can I check the libc version used by gcc 4.4.4, because /lib/libc.so.6 shows the glibc used by gcc 4.1.2, since it is the default compiler.

Answer 1

even easier
use ldd --version
This should return the glibc version being used i.e.
$ ldd --version
ldd (GNU libc) 2.17
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
...
which is the same result as running my libc library
$ /lib/libc.so.6
GNU C Library (GNU libc) stable release version 2.17, by Roland McGrath et al.
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
...

Answer 2

Write a test program (name it for example glibc-version.c):
#include <stdio.h>
#include <stdlib.h>
#include <gnu/libc-version.h>
int main(int argc, char *argv[]) {
printf("GNU libc version: %s\n", gnu_get_libc_version());
exit(EXIT_SUCCESS);
}
and compile it with the gcc-4.4 compiler:
gcc-4.4 glibc-version.c -o glibc-version
When you execute ./glibc-version the used glibc version is shown.

Answer 3

Use -print-file-name gcc option:
$ gcc -print-file-name=libc.so
/usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/libc.so
That gives the path. Let's examine the file:
$ file $(gcc -print-file-name=libc.so)
/usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/libc.so: ASCII text
$ cat $(gcc -print-file-name=libc.so)
/* GNU ld script
Use the shared library, but some functions are only in
the static library, so try that secondarily. */
OUTPUT_FORMAT(elf64-x86-64)
GROUP ( /lib/x86_64-linux-gnu/libc.so.6 /usr/lib/x86_64-linux-gnu/libc_nonshared.a AS_NEEDED ( /lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 ) )
The file is a linker script, which links the libraries in GROUP list.
On ELF platforms /lib/x86_64-linux-gnu/libc.so.6 is a position-independent executable with a dynamic symbol table (like that of a shared library):
$ file /lib/x86_64-linux-gnu/libc.so.6
/lib/x86_64-linux-gnu/libc.so.6: symbolic link to libc-2.31.so
$ file $(readlink -f /lib/x86_64-linux-gnu/libc.so.6)
/usr/lib/x86_64-linux-gnu/libc-2.31.so: ELF 64-bit LSB shared object, x86-64, version 1 (GNU/Linux), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=1878e6b475720c7c51969e69ab2d276fae6d1dee, for GNU/Linux 3.2.0, stripped
$ /lib/x86_64-linux-gnu/libc.so.6
GNU C Library (Ubuntu GLIBC 2.31-0ubuntu9.9) stable release version 2.31.
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.
Compiled by GNU CC version 9.4.0.
libc ABIs: UNIQUE IFUNC ABSOLUTE
For bug reporting instructions, please see:
<https://bugs.launchpad.net/ubuntu/+source/glibc/+bugs>.

Answer 4

gnu_get_libc_version identifies the runtime version of the GNU C Library.
If what you care about is the compile-time version (that is, the version that provided the headers in /usr/include), you should look at the macros __GLIBC__ and __GLIBC_MINOR__. These expand to positive integers, and will be defined as a side-effect of including any header file provided by the GNU C Library; this means you can include a standard header, and then use #ifdef __GLIBC__ to decide whether you can include a nonstandard header like gnu/libc-version.h.
Expanding the test program from the accepted answer:
#include <stdio.h>
#ifdef __GLIBC__
#include <gnu/libc-version.h>
#endif
int
main(void)
{
#ifdef __GLIBC__
printf("GNU libc compile-time version: %u.%u\n", __GLIBC__, __GLIBC_MINOR__);
printf("GNU libc runtime version: %s\n", gnu_get_libc_version());
return 0;
#else
puts("Not the GNU C Library");
return 1;
#endif
}
When I compile and run this program on the computer I'm typing this answer on (which is a Mac) it prints
Not the GNU C Library
but when compiled and run on a nearby Linux box it prints
GNU libc compile-time version: 2.24
GNU libc runtime version: 2.24
Under normal circumstances, the "runtime" version could be bigger than the "compile-time" version, but never smaller. The major version number is unlikely ever to change again (the last time it changed was the "libc6 transition" in 1997).
If you would prefer a shell 'one-liner' to dump these macros, use:
echo '#include <errno.h>' | gcc -xc - -E -dM |
grep -E '^#define __GLIBC(|_MINOR)__ ' | sort
The grep pattern is chosen to match only the two macros that are relevant, because there are dozens of internal macros named __GLIBC_somethingorother that you don't want to have to read through.

Answer 5

I doubt if you have more than one glibc installed in your system.But ldd -v <path/to/gcc-4.x> should give you the glibc used.

Answer 6

The easiest way is to use ldd which comes with glibc
Just run this command ldd --version :
dina#dina-X450LA:~$ ldd --version
ldd (Ubuntu GLIBC 2.23-0ubuntu9) 2.23
Copyright (C) 2016 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Written by Roland McGrath and Ulrich Drepper.
Their is two additional ways to find out the glibc version:
Check the version of the installed glibc rpm package : this by runing this command
rpm -q glibc
Check the version of the used libc.so file. This way is a little bit more difficult. You can check it in this link: Linux: Check the glibc version

Answer 7

You can use strings command to check GLIBC version of compiler. Highest version is applicable.
ubuntu1604:extra$ strings ./arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-gcc | grep GLIBC
GLIBC_2.3
GLIBC_2.8
GLIBC_2.14
GLIBC_2.4
GLIBC_2.11
GLIBC_2.2.5
GLIBC_2.3.4

Answer 8

Also, check the higher versioning symbol of the libc:
readelf -V /lib64/libc.so.6