快连VPN:速度和安全性最佳的VPN服务
通常，開發人員和運維人員在處理軟件運行時報錯找不到依賴庫的問題時，可以使用一些工具來跟蹤啓動加載的過程，比如strace、gdb等。此外，還可以利用ld和ldd命令來幫助分析依賴庫的情況，以便更快地解決問題。這些工具可以幫助定位缺少的依賴庫，並指導用戶採取適當的措施來解決軟件運行時的問題。
這裏以分析 libmpi_usempif80.so 這個動態庫文件，依賴哪些其他動態庫，作爲問題起因。
首先介紹 ld 命令如何幫我們分析mpi_usempif80 庫依賴其他哪些庫？mpi_usempif80 庫被加載時，會從當前系統的哪些路徑下搜索這些庫？
#ld -lmpi_usempif08 –verbose
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Symbols in the DWARF debugging sections are relative to the beginning of the section so we begin them at 0.*//* DWARF 1.*/.debug0 : { *(.debug) }.line 0 : { *(.line) }/* GNU DWARF 1 extensions.*/.debug_srcinfo0 : { *(.debug_srcinfo) }.debug_sfnames0 : { *(.debug_sfnames) }/* DWARF 1.1 and DWARF 2.*/.debug_aranges0 : { *(.debug_aranges) }.debug_pubnames 0 : { *(.debug_pubnames) }/* DWARF 2.*/.debug_info 0 : { *(.debug_info .gnu.linkonce.wi.*) }.debug_abbrev 0 : { *(.debug_abbrev) }.debug_line 0 : { *(.debug_line .debug_line.* .debug_line_end) }.debug_frame0 : { *(.debug_frame) }.debug_str0 : { *(.debug_str) }.debug_loc0 : { *(.debug_loc) }.debug_macinfo0 : { *(.debug_macinfo) }/* SGI/MIPS DWARF 2 extensions.*/.debug_weaknames 0 : { *(.debug_weaknames) }.debug_funcnames 0 : { *(.debug_funcnames) }.debug_typenames 0 : { *(.debug_typenames) }.debug_varnames0 : { *(.debug_varnames) }/* DWARF 3.*/.debug_pubtypes 0 : { *(.debug_pubtypes) }.debug_ranges 0 : { *(.debug_ranges) }/* DWARF 5.*/.debug_addr 0 : { *(.debug_addr) }.debug_line_str 0 : { *(.debug_line_str) }.debug_loclists 0 : { *(.debug_loclists) }.debug_macro0 : { *(.debug_macro) }.debug_names0 : { *(.debug_names) }.debug_rnglists 0 : { *(.debug_rnglists) }.debug_str_offsets 0 : { *(.debug_str_offsets) }.debug_sup0 : { *(.debug_sup) }.gnu.attributes 0 : { KEEP (*(.gnu.attributes)) }/DISCARD/ : { *(.note.GNU-stack) *(.gnu_debuglink) *(.gnu.lto_*) }}==================================================ld: mode elf_x86_64attempt to open /usr/local/lib/x86_64-linux-gnu/libmpi_usempif08.so failedattempt to open /usr/local/lib/x86_64-linux-gnu/libmpi_usempif08.a failedattempt to open /lib/x86_64-linux-gnu/libmpi_usempif08.so succeeded/lib/x86_64-linux-gnu/libmpi_usempif08.solibmpi_mpifh.so.40 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.soattempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libmpi_mpifh.so.40 failedattempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libmpi_mpifh.so.40 failedattempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libmpi_mpifh.so.40 failedattempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libmpi_mpifh.so.40 failedattempt to open /usr/local/lib/libmpi_mpifh.so.40 failedfound libmpi_mpifh.so.40 at /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40libmpi.so.40 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.soattempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libmpi.so.40 failedattempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libmpi.so.40 failedattempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libmpi.so.40 failedattempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libmpi.so.40 failedattempt to open /usr/local/lib/libmpi.so.40 failedfound libmpi.so.40 at /usr/lib/x86_64-linux-gnu/libmpi.so.40libc.so.6 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.soattempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libc.so.6 failedattempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libc.so.6 failedattempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libc.so.6 failedattempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libc.so.6 failedattempt to open /usr/local/lib/libc.so.6 failedattempt to open /usr/lib/x86_64-linux-gnu/fortran/gfortran/libc.so.6 failedattempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libc.so.6 failedattempt to open /usr/local/lib/x86_64-linux-gnu/libc.so.6 failedattempt to open /usr/local/lib/x86_64-linux-gnu/libc.so.6 failedattempt to open /usr/lib/x86_64-linux-gnu64/libc.so.6 failedattempt to open /usr/local/lib64/libc.so.6 failedattempt to open /lib64/libc.so.6 failedattempt to open /usr/lib64/libc.so.6 failedattempt to open /usr/local/lib/libc.so.6 failedattempt to open /lib/libc.so.6 failedattempt to open /usr/lib/libc.so.6 failedattempt to open /usr/x86_64-linux-gnu/lib64/libc.so.6 failedattempt to open /usr/x86_64-linux-gnu/lib/libc.so.6 failedattempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libc.so.6 failedattempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libc.so.6 failedattempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libc.so.6 failedattempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libc.so.6 failedattempt to open /usr/local/lib/libc.so.6 failedfound libc.so.6 at /usr/lib/x86_64-linux-gnu/libc.so.6libopen-pal.so.40 needed by /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libopen-pal.so.40 failedattempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/opal/.libs/libopen-pal.so.40 failedattempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libopen-pal.so.40 failedattempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libopen-pal.so.40 failedattempt to open /usr/local/lib/libopen-pal.so.40 failedfound libopen-pal.so.40 at /usr/lib/x86_64-linux-gnu/libopen-pal.so.40libopen-rte.so.40 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libopen-rte.so.40 failedattempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libopen-rte.so.40 failedattempt to open /usr/local/lib/libopen-rte.so.40 failedfound libopen-rte.so.40 at /usr/lib/x86_64-linux-gnu/libopen-rte.so.40libm.so.6 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libm.so.6 failedattempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libm.so.6 failedattempt to open /usr/local/lib/libm.so.6 failedfound libm.so.6 at /usr/lib/x86_64-linux-gnu/libm.so.6libhwloc.so.15 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libhwloc.so.15 failedattempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libhwloc.so.15 failedattempt to open /usr/local/lib/libhwloc.so.15 failedfound libhwloc.so.15 at /usr/lib/x86_64-linux-gnu/libhwloc.so.15ld-linux-x86-64.so.2 needed by /usr/lib/x86_64-linux-gnu/libc.so.6attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/ld-linux-x86-64.so.2 failedattempt to open /usr/local/lib/ld-linux-x86-64.so.2 failedfound ld-linux-x86-64.so.2 at /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2libevent_core-2.1.so.7 needed by /usr/lib/x86_64-linux-gnu/libopen-pal.so.40attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libevent_core-2.1.so.7 failedattempt to open /usr/local/lib/libevent_core-2.1.so.7 failedfound libevent_core-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.7libevent_pthreads-2.1.so.7 needed by /usr/lib/x86_64-linux-gnu/libopen-pal.so.40attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libevent_pthreads-2.1.so.7 failedattempt to open /usr/local/lib/libevent_pthreads-2.1.so.7 failedfound libevent_pthreads-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7libz.so.1 needed by /usr/lib/x86_64-linux-gnu/libopen-rte.so.40attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libz.so.1 failedattempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libz.so.1 failedattempt to open /usr/local/lib/libz.so.1 failedfound libz.so.1 at /usr/lib/x86_64-linux-gnu/libz.so.1libudev.so.1 needed by /usr/lib/x86_64-linux-gnu/libhwloc.so.15attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libudev.so.1 failedattempt to open /usr/local/lib/libudev.so.1 failedfound libudev.so.1 at /usr/lib/x86_64-linux-gnu/libudev.so.1ld -lmpi_usempif08 --verbose | grep foundfound libmpi_mpifh.so.40 at /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40found libmpi.so.40 at /usr/lib/x86_64-linux-gnu/libmpi.so.40ld: warning: cannot find entry symbol _start; not setting start addressfound libc.so.6 at /usr/lib/x86_64-linux-gnu/libc.so.6found libopen-pal.so.40 at /usr/lib/x86_64-linux-gnu/libopen-pal.so.40found libopen-rte.so.40 at /usr/lib/x86_64-linux-gnu/libopen-rte.so.40found libm.so.6 at /usr/lib/x86_64-linux-gnu/libm.so.6found libhwloc.so.15 at /usr/lib/x86_64-linux-gnu/libhwloc.so.15found ld-linux-x86-64.so.2 at /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2found libevent_core-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.7found libevent_pthreads-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7found libz.so.1 at /usr/lib/x86_64-linux-gnu/libz.so.1found libudev.so.1 at /usr/lib/x86_64-linux-gnu/libudev.so.1登錄後複製上面這段信息很長，有很多有價值的信息，如果你只想看關鍵部分，那麼我保留其中的關鍵內容，來一個精華版的輸出信息：
#ld -lmpi_usempif08 –verbose
GNU ld (GNU Binutils for Ubuntu) 2.38Supported emulations: elf_x86_64……using internal linker script: notice and this notice are preserved.*/OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64", "elf64-x86-64")OUTPUT_ARCH(i386:x86-64)ENTRY(_start)# 運行時可執行文件從代碼段的 _start 位置開始運行。# 運行時需從哪些目錄找動態庫文件SEARCH_DIR("=/usr/local/lib/x86_64-linux-gnu"); SEARCH_DIR("=/lib/x86_64-linux-gnu"); SEARCH_DIR("=/usr/lib/x86_64-linux-gnu"); SEARCH_DIR("=/usr/lib/x86_64-linux-gnu64"); SEARCH_DIR("=/usr/local/lib64"); SEARCH_DIR("=/lib64"); SEARCH_DIR("=/usr/lib64"); SEARCH_DIR("=/usr/local/lib"); SEARCH_DIR("=/lib"); SEARCH_DIR("=/usr/lib"); SEARCH_DIR("=/usr/x86_64-linux-gnu/lib64"); SEARCH_DIR("=/usr/x86_64-linux-gnu/lib");# 二進制文件有哪些的代碼段、數據段SECTIONS{PROVIDE (__executable_start = SEGMENT_START("text-segment", 0x400000)); . = SEGMENT_START("text-segment", 0x400000) + SIZEOF_HEADERS;.interp : { *(.interp) }…….rodata : { *(.rodata .rodata.* .gnu.linkonce.r.*) }……/* Thread Local Storage sections*/# 線程本地存儲區域.tdata : { PROVIDE_HIDDEN (__tdata_start = .); *(.tdata .tdata.* .gnu.linkonce.td.*) }.tbss: { *(.tbss .tbss.* .gnu.linkonce.tb.*) *(.tcommon) }.preinit_array:{PROVIDE_HIDDEN (__preinit_array_start = .);KEEP (*(.preinit_array))PROVIDE_HIDDEN (__preinit_array_end = .);}# 數據區.data :{*(.data .data.* .gnu.linkonce.d.*)SORT(CONSTRUCTORS)}.data1: { *(.data1) }_edata = .; PROVIDE (edata = .);. = .;__bss_start = .;# BSS區.bss:{ ……} ……}# 下面是本文的重點關注部分==================================================# 文件1：逐個目錄匹配是否找到被依賴的libmpi_usempif08.so 庫文件ld: mode elf_x86_64attempt to open /usr/local/lib/x86_64-linux-gnu/libmpi_usempif08.so failedattempt to open /usr/local/lib/x86_64-linux-gnu/libmpi_usempif08.a failedattempt to open /lib/x86_64-linux-gnu/libmpi_usempif08.so succeeded# 找到了 libmpi_usempif08.so 庫文件# 文件2：逐個目錄匹配是否找到被依賴的 libmpi_mpifh.so 庫文件libmpi_mpifh.so.40 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.soattempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libmpi_mpifh.so.40 failedattempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libmpi_mpifh.so.40 failedattempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libmpi_mpifh.so.40 failedattempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libmpi_mpifh.so.40 failedattempt to open /usr/local/lib/libmpi_mpifh.so.40 failedfound libmpi_mpifh.so.40 at /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40# 找到了 libmpi_mpifh.so 庫文件# 找 libmpi.so.40 libmpi.so.40 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so……found libmpi.so.40 at /usr/lib/x86_64-linux-gnu/libmpi.so.40# 找 libc.so.6 libc.so.6 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so……found libc.so.6 at /usr/lib/x86_64-linux-gnu/libc.so.6# 找 libopen-pal.so.40libopen-pal.so.40 needed by /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40……found libopen-pal.so.40 at /usr/lib/x86_64-linux-gnu/libopen-pal.so.40# 找 libopen-rte.so.40libopen-rte.so.40 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40……found libopen-rte.so.40 at /usr/lib/x86_64-linux-gnu/libopen-rte.so.40# 找 libm.so.6libm.so.6 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40……found libm.so.6 at /usr/lib/x86_64-linux-gnu/libm.so.6libhwloc.so.15 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40# 找 libhwloc.so.15……略# 找 libudev.so.1libudev.so.1 needed by /usr/lib/x86_64-linux-gnu/libhwloc.so.15attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libudev.so.1 failedattempt to open /usr/local/lib/libudev.so.1 failedfound libudev.so.1 at /usr/lib/x86_64-linux-gnu/libudev.so.1登錄後複製進一步，我們可以用 grep 過濾只顯示 mpi_usempif08 實際找到的庫的信息：
#ld -lmpi_usempif08 –verbose | grep found
found libmpi_mpifh.so.40 at /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40found libmpi.so.40 at /usr/lib/x86_64-linux-gnu/libmpi.so.40ld: warning: cannot find entry symbol _start; not setting start addressfound libc.so.6 at /usr/lib/x86_64-linux-gnu/libc.so.6found libopen-pal.so.40 at /usr/lib/x86_64-linux-gnu/libopen-pal.so.40found libopen-rte.so.40 at /usr/lib/x86_64-linux-gnu/libopen-rte.so.40found libm.so.6 at /usr/lib/x86_64-linux-gnu/libm.so.6found libhwloc.so.15 at /usr/lib/x86_64-linux-gnu/libhwloc.so.15found ld-linux-x86-64.so.2 at /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2found libevent_core-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.7found libevent_pthreads-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7found libz.so.1 at /usr/lib/x86_64-linux-gnu/libz.so.1found libudev.so.1 at /usr/lib/x86_64-linux-gnu/libudev.so.1登錄後複製
而ldd 與 ld是不同的。ldd是分析linux的運行庫的依賴關係、ld是可執行文件鏈接器常用於C/C++/Fortran等語言代碼生成可執行文件的鏈接階段。
我們看下 使用 ldd 對同一個動態庫所依賴的其他庫的分析：
#ldd/usr/lib/x86_64-linux-gnu/libmpi_usempif08.so.40.30.0
linux-vdso.so.1 (0x00007ffd2f3fd000) libmpi_mpifh.so.40 => /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40 (0x00007f34366bf000) libmpi.so.40 => /usr/lib/x86_64-linux-gnu/libmpi.so.40 (0x00007f3436588000) libc.so.6 => /usr/lib/x86_64-linux-gnu/libc.so.6 (0x00007f3436200000) libopen-pal.so.40 => /usr/lib/x86_64-linux-gnu/libopen-pal.so.40 (0x00007f34364d5000) libopen-rte.so.40 => /usr/lib/x86_64-linux-gnu/libopen-rte.so.40 (0x00007f3436143000) libm.so.6 => /usr/lib/x86_64-linux-gnu/libm.so.6 (0x00007f343605c000) libhwloc.so.15 => /usr/lib/x86_64-linux-gnu/libhwloc.so.15 (0x00007f3436477000) /lib64/ld-linux-x86-64.so.2 (0x00007f343677c000) libevent_core-2.1.so.7 => /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.7 (0x00007f3436442000) libevent_pthreads-2.1.so.7 => /usr/lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7 (0x00007f343643d000) libz.so.1 => /usr/lib/x86_64-linux-gnu/libz.so.1 (0x00007f3436040000) libudev.so.1 => /usr/lib/x86_64-linux-gnu/libudev.so.1 (0x00007f3436016000)登錄後複製
這裏的順序與ld -lmpi_usempif08 –verbose | grep found 的結果是一致的。
以上就是漲知識了，Linux的ld和ldd一起用，可以幫我們分析運行時加載庫文件失敗的原因的詳細內容，更多請關注本站其它相關文章！
