====== Linker ======

Alternatives:

  * GNU BFD Linker <
  * gold <
  * LLD <
  * mold <

====== Links ======

===== General =====

FIXME

====== Docs ======

FIXME

====== Articles ======

[[https://www.heise.de/select/ix/archiv/2022/12/seite-112|iX 12/2022 - Page 112 - Ohne Linker kein Programm]]\\
[[https://www.heise.de/select/ix/archiv/2023/2/seite-136|iX 02/2023 - Page 136 - Mit dem richtigen Linker Zeit sparen]]\\
[[https://www.linux-magazin.de/ausgaben/2023/08/ld-preload/|Linux-Magazin 08/2023 - Page 70 - Programmverhalten mit LD_PRELOAD ändern]]\\

====== Files and Directories ======

FIXME

===== General Files and Directories =====

FIXME

===== Configuration Files =====

FIXME

====== Getting Help ======

//binutils// Manual pages: 

<cli>
user@host:~$ man 1 ld
user@host:~$ man 1 nm
user@host:~$ man 1 objdump
user@host:~$ man 1 readelf
user@host:~$ man 1 strip
</cli>

//GNU C Library: Binaries// Manual pages: 

<cli>
user@host:~$ man 1 ldd
</cli>

//Dynamically linked library call tracer// Manual pages: 

<cli>
user@host:~$ man 1 ltrace
</cli>

//System call tracer// Manual pages: 

<cli>
user@host:~$ man 1 strace
</cli>

====== Install ======

To install the //GNU assembler, linker and binary utilities// on Debian:

<cli>
root@host:~$ apt-get -y install binutils binutils-common
</cli> 

To install the documentation for the //GNU assembler, linker and binary utilities// on Debian:

<cli>
root@host:~$ apt-get -y install binutils-doc
</cli> 

To install the //Dynamically linked library call tracer// on Debian:

<cli>
root@host:~$ apt-get -y install ltrace
</cli> 

To install the //System call tracer// on Debian:

<cli>
root@host:~$ apt-get -y install strace
</cli> 

====== Configuration ======

FIXME

====== Usage ======

===== Using an alternative Linker =====

  * Create a symlink of ''/usr/bin/ld'' to the linker of choice <
  * Use of ''LDFLAGS'' environment variable and there ''-fuse-ld='', but this depends on support for the specific linker in the used compiler (e.g. GCC, Clang, ...) <
  * Workaround: Create a directory e.g. ''tools'', create a symlink to the linker of choice in there and use the option ''-Btools'' in the ''LDFLAGS'' environment variable. <

===== Listing all exported symbols of a library =====

<cli>
root@host:~$ readelf -Ws <LIBRARY_FILE>
</cli>

===== Changing the loaded shared libraries =====

Setting the environment variables ''LD_LIBRARY_PATH'' or ''LD_PRELOAD'' in order to change the search order of the linked shared libraries to be loaded at start of a binary.

===== Tracing the system calls of a program =====

To trace the system calls (i.e. Linux kernel calls) of a program upon execution: 

<cli>
root@host:~$ strace -f <PROGRAMM>
</cli>

===== Tracing the dynamically linked library calls of a program =====

To trace the calls to symbols exported by dynamically linked libraries of a program upon execution: 

<cli>
root@host:~$ ltrace -f <PROGRAM> 
</cli>

====== Recipies ======

FIXME

<nspages .:recipies -subns -pagesInNs -simpleList -title -hideNoSubns -hideNoPages -textNS="" -exclude:start>

====== Known Issues ======

FIXME