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File Naming Conventions
-=-=-=-=-=-=-=-=-=-=-=-
sqsh_*.[ch] All files beginning with sqsh_*.[ch] are core functions to
the shell, they define functions that are called or do call
user defined functions.
cmd_*.[ch] These are the source behind the commands that may be
invoked by a user.
var_*.[ch] These are validation functions for setting and retrieving
environment variables.
Modules
-=-=-=-=-
sqsh_fd.c - Most libc functions that deal with file descriptors
or FILE structures are replaced here with sqsh equiv-
alents (they attempt to be a little smarter). All
file access should be performed through these function.
sqsh_global.c - Contains definitions for all global variables. These
are such variables as the DBPROCESS connection to the
database, and the environment structure to contain all
environment variables.
sqsh_init.c - Where all globals defined in sqsh_global.[ch] are
initialized to thier default values, this includes
setting up default values for system-supplied
environment variables.
sqsh_fork.c - Fork replacement function for starting a child process.
This is responsible for re-initializing any global
variables defined in sqsh_global.[ch] for use by the
child (for example, the child should not inherit the
parent's DBPROCESS pointer).
sqsh_sigcld.c - Functions for queueing SIGCLD (or SIGCHLD) events for
later processing. These functions are used in jobset_*()
functions and sqsh_popen() functions.
Error Condititions
-=-=-=-=-=-=-=-=-=-
There are only three places in which actual printfs should be called:
1. In any user-defined cmd_*() functions.
2. In sqsh_main.c to report configuration errors, etc.
3. Any asyncronous signal handlers (sqsh_sigcld.c: sigcld_handler(),
in particular).
In all other functions and modules error conditions should be returned
via return codes and setting error conditions with sqsh_set_error().
All functions that don't fit criterea 1 or 2, above, should aways call
sqsh_set_error() to identify an error condition, even if no error ocurres
(in this case it would be sqsh_set_error( SQSH_E_NONE, NULL ).
Shell Misfeatures
-=-=-=-=-=-=-=-=-
Unlike most shells, sqsh expands all variables on the command line first
then tokenizes the command line, so if it is known or thought that a
variable may contain white-space then it should be quoted.
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