Here is an overview of the source code organization for ksh93. Directory layout: The directory include contains header files for ksh93. The files nval.h and shell.h are intended to be public headers and can be used to add runtime builtin command. The remainder are private. The directory data contains readonly data files for ksh93. The man pages for built-ins are in builtins.c rather than included as statics with the implementations in the bltins directory because some systems don't make static const data readonly and we want these to be shared by all running shells. The directory edit contains the code for command line editing and history. The fun directory contains some shell function such as pushd, popd, and dirs. The directory features contains files that are used to generate header files in the FEATURE directory. Most of these files are in a format that is processed by iffe. The directory bltins contains code for most of the built-in commands. Additional built-in commands are part of libcmd. The directory sh contains most of the code for ksh93. The directory tests contains a number of regression tests. In most cases, when a bug gets fixed, a test is added to one of these files. The regression tests can be run by going to this directory and running SHELL=shell_path shell_path shtests where shell_path is an absolute pathname for the shell to be tested. The top level directory contains the nmake Makefile, a README, and several documentation files. The RELEASE file contains the list of bug fixes and new features since the original ksh93 release. The file COMPATIBILITY is a list of all known incompatibilities with ksh88. The bash_pre_rc.sh is a startup script used when emulating bash if the shell is compiled with SHOPT_BASH and the shell is invoked as bash. The bash emulation is not complete. Include directory: 1. argnod.h contains the type definitions for command nodes, io nodes, argument nodes, and for positional parameters.a It defines the prototypes for all the positional parameters functions. 2. builtins.h contains prototypes for builtins as well as symbolic constants that refer to the name-pairs that are associated with some of the built-ins. It also contains prototypes for many of the strings. 3. defs.h is the catch all for all definitions that don't fit elsewhere and it includes several other headers. It defines a strucuture that contains ksh global data, sh, and a structure that contains per function data, sh.st. 4. edit.h contains definitions that are common to both vi and emacs edit modes. 5. env.h contains interfaces for creating and modifying environment variables. 6. fault.h contains prototypes for signal related functions and trap and fault handling. 7. fcin.h contains macro and function definitions for reading from a file or string. 8. history.h contains macros and functions definitions related to history file processing. 9. jobs.h contains the definitions relating to job processing and control. 10. lexstates.h contains the states associated with lexical processing. 11. name.h contains the internal definitions related to name-value pair processing. 12. national.h contains a few I18N definitions, mostly obsolete. 13. nval.h is the public interface to the name-value pair library that is documented with nval.3. 14. path.h contains the interface for pathname processing and pathname searching. 15. shell.h is the public interface for shell functions that are documented int shell.3. 16. shlex.h contains the lexical token definitions and interfaces for lexical analysis. 17. shnodes.h contains the definition of the structures for each of the parse nodes and flags for the attributes. 18. shtable.h contains some interfaces and functions for table lookup. 19. streval.h contains the interface to the arithmetic functions. 20. terminal.h is a header file that includes the appropriate terminal include. 21. test.h contains the definitions for the test and [[...]] commands. 22. timeout.h contains the define constant for the maximum shell timeout. 23. ulimit.h includes the appropriate resource header. 24. variables.h contains symbolic constants for the built-in shell variables. sh directory: 1. args.c contains functions for parsing shell options and for processing positional parameters. 2. arith.c contains callback functions for the streval.c library and the interface to shell arithmetic. 3. array.c contains the code for indexed and associative arrays. 4. bash.h contains code used when compiling with SHOPT_BASH to add bash specific features such as shopt. 5. defs.c contains the data definitions for global symbols. 6. deparse.c contains code to generate shell script from a parse tree. 7. env.c contains code to add and delete environment variables to an environment list. 8. expand.c contains code for file name expansion and file name generation. 9. fault.c contains code for signal processing, trap handling and termination. 10. fcin.c contains code for reading and writing a character at a time from a file or string. 11. init.c contains initialization code and callbacks for get and set functions for built-in variables. 12. io.o contains code for redirections and managing file descriptors and file streams. 13. jobs.c contains the code for job management. 14. lex.c contains the code for the lexical analyzer. 15. macro.c contains code for the $ macro expansions, including here-documents. 16. main.c contains the calls to initialization, profile processing and the main evaluation loop as well as mail processing. 17. name.c contains the name-value pair routines that are built on the hash library in libast. 18. nvdisc.c contains code related to name-value pair disciplines. 19. nvtree.c contains code for compound variables and for walking the namespace. 20. nvtype.c contains most of the code related to types that are created with typeset -T. 21. parse.c contains the code for the shell parser. 22. path.c contains the code for pathname lookup and some path functions. It also contains the code that executes commands and scripts. 23. pmain.c is just a calls sh_main() so that all of the rest of the shell can be in a shared library. 24. shcomp.c contains the main program to the shell compiler. This program parses a script and creates a file that the shell can read containing the parse tree. 25. streval.c is an C arithmetic evaluator. 26. string.c contains some string related functions. 27. subshell.c contains the code to save and restore environments so that subshells can run without creating a new process. 28. suid_exec.c contains the program from running execute only and/or setuid/setgid scripts. 29. tdump.c contains the code to dump a parse tree into a file. 30. timers.c contains code for multiple event timeouts. 31. trestore contians the code for restoring the parse tree from the file created by tdump. 32. userinit.c contains a dummy userinit() function. This is now obsolete with the new version of sh_main(). 33. waitevent.c contains the sh_waitnotify function so that builtins can handle processing events when the shell is waiting for input or for process completion. 34. xec.c is the main shell executuion loop.