AWKLIBPATH Variable (The GNU Awk User’s Guide)
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2.5.2 The AWKLIBPATH Environment Variable
The AWKLIBPATH environment variable is similar to the AWKPATH variable, but it is used to search for loadable extensions (stored as system shared libraries) specified with the -l option rather than for source files. If the extension is not found, the path is searched again after adding the appropriate shared library suffix for the platform. For example, on GNU/Linux systems, the suffix ‘.so’ is used. The search path specified is also used for extensions loaded via the @load keyword (see section Loading Dynamic Extensions into Your Program).
If AWKLIBPATH does not exist in the environment, or if it has an empty value, gawk uses a default path; this is typically ‘/usr/local/lib/gawk’, although it can vary depending upon how gawk was built.15
See section Shell Startup Files, for information on functions that help to manipulate the AWKLIBPATH variable.
gawk places the value of the search path that it used into ENVIRON["AWKLIBPATH"]. This provides access to the actual search path value from within an awk program.
Although you can change ENVIRON["AWKLIBPATH"] within your awk program, this has no effect on the running program’s behavior. This makes sense: the AWKLIBPATH environment variable is used to find any requested extensions, and they are loaded before the program starts to run. Once your program is running, all the extensions have been found, and gawk no longer needs to use AWKLIBPATH.
Footnotes
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Your version of gawk may use a different directory; it will depend upon how gawk was built and installed. The actual directory is the value of $(pkgextensiondir) generated when gawk was configured. (For more detail, see the INSTALL file in the source distribution, and see Compiling gawk for Unix-Like Systems. You probably don’t need to worry about this, though.)
