NAME

find_elf - Locate ELF shared objects and executables

SYNOPSIS

find_elf [-afrs] path

DESCRIPTION

The find_elf command descends a directory hierarchy and produces one line of output on stdout for each ELF executable or shared object found.

OPTIONS

The following options are supported:

-a: Disable alias processing. Symbolic links are treated as independent files, each such link results in a separate OBJECT output line, and ALIAS lines are not issued.

-f: Fast Mode. When reading directories, the file name and modes are used to eliminate files from consideration and speed up the search: Directories with names that start with a '.' character are skipped. Executables must have the execute bit set, and shared objects must end with a .so extension. Files that do not meet these requirements are silently eliminated from consideration without further analysis.

-r: Report file names as relative paths, relative to the given file or directory, instead of fully qualified.

-s: Only report shared objects.

OUTPUT

find_elf produces a series of PREFIX, OBJECT, and ALIAS lines, which collectively describe the ELF objects located. Whitespace is used within each line to delimit the various fields of information provided.

If the -r option is used to specify that file names be reported as relative paths, a PREFIX line is output to provide the base path from which the relative names should be interpreted. There can only be one PREFIX line, and it is output first, before any OBJECT or ALIAS lines.

PREFIX path

For each object found, an OBJECT line is produced to describe it:

OBJECT [32 | 64] [DYN | EXEC] [VERDEF | NOVERDEF] object-path

The first field provides the ELF class of the object, and will be either 32 or 64. The second field provides the type of object, either a shared object (DYN) or executable (EXEC). The third field will be VERDEF if the object contains ELF version definitions, and NOVERDEF if the object is not versioned. The final field gives the path to the object.

Under Unix, a file can have multiple names. In the context of ELF objects, this often happens for one of two reasons:

o: Compilation symlinks, used to provide a non-versioned name for a shared object.

o: Symlinks such as '32' and '64' used to provide alternative non-machine specific paths to objects.

When find_elf identifies an object via such an aliased name, it issues an ALIAS line mapping it to the main name for the object:

ALIAS object-path alias-path

The -a option alters the handling of aliased names. When -a is specified, each file results in a separate OBJECT line, as if they were independent files rather than the same file with different names.

EXAMPLES

Assume the following hierarchy of files exist under /usr/lib/foo:

% /bin/ls -alRF /usr/lib/foo
/usr/lib/foo:
total 111
drwxr-xr-x 3 root root 7 Jul 16 17:35 ./
drwxr-xr-x 34 root root 42 Jul 16 17:34 ../
lrwxrwxrwx 1 root bin 1 Jul 16 17:34 32 -> ./
lrwxrwxrwx 1 root bin 5 Jul 16 17:34 64 -> amd64/
drwxr-xr-x 2 root bin 4 Jul 16 17:35 amd64/
lrwxrwxrwx 1 root bin 11 Jul 16 17:35 libfoo.so -> libfoo.so.1*
-rwxr-xr-x 1 root bin 49132 Jul 16 17:35 libfoo.so.1*

/usr/lib/foo/amd64:
total 150
drwxr-xr-x 2 root root 4 Jul 16 17:35 ./
drwxr-xr-x 3 root root 7 Jul 16 17:35 ../
lrwxrwxrwx 1 root bin 11 Jul 16 17:35 libfoo.so -> libfoo.so.1*
-rwxr-xr-x 1 root bin 72536 Jul 16 17:35 libfoo.so.1*

This hierarchy contains compilation symlinks (libfoo.so) and path alias symlinks (32, 64), as discussed in OUTPUT. find_elf produces the following output for the above hierarchy:

% find_elf -r /usr/lib/foo
PREFIX /usr/lib/foo
OBJECT 64 DYN VERDEF amd64/libfoo.so.1
ALIAS amd64/libfoo.so.1 64/libfoo.so
ALIAS amd64/libfoo.so.1 64/libfoo.so.1
ALIAS amd64/libfoo.so.1 amd64/libfoo.so
OBJECT 32 DYN VERDEF libfoo.so.1
ALIAS libfoo.so.1 32/libfoo.so
ALIAS libfoo.so.1 32/libfoo.so.1
ALIAS libfoo.so.1 libfoo.so

Contrast this with the output when -a is used to treat each name as an independent file:

% find_elf -ar /usr/lib/foo
PREFIX /usr/lib/foo
OBJECT 32 DYN VERDEF 32/libfoo.so
OBJECT 32 DYN VERDEF 32/libfoo.so.1
OBJECT 64 DYN VERDEF 64/libfoo.so
OBJECT 64 DYN VERDEF 64/libfoo.so.1
OBJECT 64 DYN VERDEF amd64/libfoo.so.1
OBJECT 64 DYN VERDEF amd64/libfoo.so
OBJECT 32 DYN VERDEF libfoo.so.1
OBJECT 32 DYN VERDEF libfoo.so

When find_elf is used to process an alias for which no target object is given, there will be no output. For example, using /lib/libc.so, which is a compilation symlink for /lib/libc.so.1:

% find_elf /lib/libc.so

In such situations, the -a option can be used to produce the desired output: