[problem]
Getting an error about not being able to find libraries (file not found), when starting up a binary – such as httpd.
[/problem]
[solution]
You need to identify the shared libraries required by your binary. Ordinarly we use the ldd command for this and amended LD_LIBRARY_PATH to find the libs – see example below.
You might also want to get the shared libs of a running process – with pldd or need to dig into a lib/binary.
[/solution]
[example]
# find dependencies for a binary
% ldd /usr/bin/httpd
libpng.so.2 => /usr/local/lib/libpng.so.2
libcrypt_i.so.1 => /usr/lib/libcrypt_i.so.1
libresolv.so.2 => /usr/lib/libresolv.so.2
…
# demo of how ldd walks the values in LD_LIBRARY_PATH
% unset LD_LIBRARY_PATH
% ldd /usr/bin/httpd
libpng.so.2 => (file not found)
libcrypt_i.so.1 => /usr/lib/libcrypt_i.so.1
libresolv.so.2 => /usr/lib/libresolv.so.2
…
# find files installed via a package on Solaris
% grep libpng.so.2 /var/sadm/install/contents | head -1
/usr/sf/lib/libpng.so=libpng.so.2 s none SUNWpng
Another way to see which libraries are being picked up, i.e. if a binary works on one system and not another:
% truss -t'open' -f date
21667: open("/var/ld/ld.config", O_RDONLY) Err#2 ENOENT
21667: open("/usr/lib/libc.so.1", O_RDONLY) = 3
21667: open("/usr/lib/libdl.so.1", O_RDONLY) = 3
...
Getting the dependent shared libraries of a running process (especially where vars might have changed since startup):
% pldd 24832
24832: /usr/bin/httpd
/usr/local/lib/libpng.so.2.1.0.5
/usr/lib/libcrypt_i.so.1
/usr/lib/libresolv.so.2
...
Seeing more detail via the headers within an object file (use objdump on linux):
% elfdump /usr/bin/httpd | grep NEEDED
[0] NEEDED 0x15755 libpng.so.2
[1] NEEDED 0x15761 libcrypt_i.so.1
[2] NEEDED 0x15771 libresolv.so.2
...
See configure parameters passed to a binary during compilation (can also be useful for getting a usage out a binary, that does not appear by default or with –h, etc):
[/example]
[reference]
[/reference]
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