when we try to set a trap on them it will not work. Also while I am here:
1. don't change the action status if the signal system call failed.
2. don't try to sigignore it if signal failed.
3. clear the signal mask in case our parent blocked it for us.
- ansification
- format of output of jobs command (etc)
- job identiers %+, %- etc
- $? and $(...)
- correct quoting of output of set, export -p and readonly -p
- differentiation between nornal and 'posix special' builtins
- correct behaviour (posix) for errors on builtins and special builtins
- builtin printf and kill
- set -o debug (if compiled with DEBUG)
- cd src obj (as ksh - too useful to do without)
- unset -e name, remove non-readonly variable from export list.
(so I could unset -e PS1 before running the test shell...)
Plus my changes:
- walking process group fix in foregrounding a job.
- reset of process group in parent shell if interrupted before the wait.
- move INTON lower in the dowait so that the job structure is
consistent.
- error check all setpgid(), tcsetpgrp() calls.
- eliminate unneeded strpgid() call.
- check that we don't belong in the process group before we try to
set it.
POSIX recommendations.
- trap now accepts signal names and signal numbers
e.g. INT, SIGINT, 2
- added option -l that outputs a list of valid signals
- added signal EXIT to list of valid signals
- a `-' in the action part will reset specified signal to their
default behaviour
- changed standard output format to make it suitable as an input
to another shell that achieves the same trapping results
The problem was that system calls got restarted after a signal,
instead of returning EINTR. Thus the read builtin, had no way to
know that a signal occured that could change the course of execution.
Since the code has sprinkled checks for EINTR all over the place,
it is supposed to work properly with non restartable syscalls.
The fix is to use siginterrupt(signo, 1), before setting a signal
handler, to make sure that system calls don't get restarted.
