The code extracts for the sample shell included in this chapter are only
a part of the entire shell program. In particular, nothing at all has
been said about how
program data structures are
allocated and initialized.
Most real shells provide a complex user interface that has support for a command language; variables; abbreviations, substitutions, and pattern matching on file names; and the like. All of this is far too complicated to explain here! Instead, we have concentrated on showing how to implement the core process creation and job control functions that can be called from such a shell.
Here is a table summarizing the major entry points we have presented:
void init_shell (void)
void launch_job (job *j
void do_job_notification (void)
SIGCHLDsignals. See Stopped and Terminated Jobs.
void continue_job (job *j
Of course, a real shell would also want to provide other functions for
managing jobs. For example, it would be useful to have commands to list
all active jobs or to send a signal (such as
SIGKILL) to a job.