⟦86ce9a48e⟧

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Problems fixed in first new shell:
	1) Interrupts leading to multiple shells.
	2) Failure to return exit value of last command.
	3) Improper treatment of assignments on same line as command.
	4) Improper treatment of initial environment and export variables.
	5) . command now uses $PATH correctly.
	6) Escaped newline between ) and | is no longer syntax error.
	7) The flags -ekntvx are now implemented and work.
	8) Here documents are supported; they don't work for detached
		processes, but no garbage is left hanging around.
	9) Parameter substitution is done in `command $X` contexts.
	10) The logical connectives && and || can now be used more than
		once in a command.
	11) Errors in command files should be on the line reported, not
		occasionally on the previous line.
	12) times now reports correct times thanks to rand.
	13) readonly now reports readonly variables thanks to tj.
	14) New shell variable SHELL determines, if set, the file to be
		run as the shell for command file execution, etc.
		defaults to /bin/sh.
	15) exec is implemented.
	16) Unimplemented built-in functions are reported as such.
	17) Illegal redirection of built-in functions is detected.
	18) set now sets the positional parameters so they aren't overwritten.

In addition to the original list, as of 16.Mar.82, fixes:
	1) Positional parameters.
	2) Commands in .profile can now print to the terminal, eg set, export,
		readonly.
	3) Line numbers of errors in files are correct.
	4) Refer to SH(1), p. 4, Environment, for an explanation of how
		export should work; that's how it works.
	5) status 16 is now reported as bus error.  From the source I can
		aver that the shell has never reported "Bus error" because
		SIGBUS has never been < NSIG.
	6) At least one cause of corrupted shared text has been eliminated.
		There may be others.

The following features have been fixed in the shell installed as /bin/nsh
on March 25, 1982:
	1) Compound commands can be piped without enclosing in ().
	2) Shell command files can be interrupted.
	3) Shell command files executing nohup processes cannot
		be interrupted.
	4) Pipes which end in a null command are reported as syntax errors.
	5) All shell output goes to stderr.
	6) Redirections named with digits works.
	7) ${n?...}, ${n-...}, ${n+...} where n is a digit works.
	8) Errors in evaluation of arguments abort that command's execution.
	9) Errors in command files abort command file execution.
	10) sh -c does an automatic exec on last command.
		Desireable?
	11) 'set - /usr/src/cmd/*.c; set ""' no longer blows the shell away.
	12) 'wait nnn' works.
	13) 'sh file' will use $PATH to search for file.
	14) $? now follows spec for status of abnormally terminated commands;
		ie $? = 200 + signal number.
	15) Here documents work for detached processes.
	16) Parts of the original environment which have not been overwritten
		by new exportables are listed by the export command.
		This allows differences between set values and export values
		to be identified.
	17) Trailing newlines of `command` results are discarded.
	18) `command` no longer requires an exec("/bin/sh", ...),
		the command is processed by a forked shell.
	19) The eval command is implemented.
	20) The read command is implemented.
	21) The trap command is implemented.
	22) com1 && com2 & works correctly, logicals have
		higher precedence than &.
	23) \* no longer gets expanded by glob, along with \? and \[.
	24) \ within "" only escapes \"$` as is correct.
	25) During command file execution, $0 is set to command file
		name instead of "sh".
	26) man command works, don't know why it broke.

New fixes for shell of April 1, 1982:
	1) The shell now executes command files with a fork.
	2) Here documents no longer have a \0 appended to each line.
	3) Illegal variable names are not accepted by read.
	4) New internal variable LASTERROR is set to name of command
		which last returned non-zero status.  Rico suggests
		that this variable be exported to "help" and "usage".
	5) PATH lookup for "sh file" commands has been deleted,  tj
		objected.
	6) The broken pipe problem is at least partially solved.  When
		the shell can't execute a pipe member, the previous
		members of the pipe will be waited out.  If a pipe
		member dies abnormally, the shell will return before
		the head of the pipe completes which may lead to a
		competition for /dev/tty.
	7) The treatments of `( list )' and `{ list; }' now follow the grammar
		specification; ie `(' and `)' are recognized anywhere
		unless quoted, `{' and `}' are recognized only as the
		first word of a command.

New fixes for shell of April 16, 1982:
	1) Execution of shell command files from the editor is fixed.
	2) Case patterns are now evaluated so they may contain quoted
		glob characters, quoted shell tokens, $variables, etc.
	3) Glob character quoting is now done with \ so no 0200 flags
		are used by the shell.
	4) /etc/glob has been modified to save the exec of /bin/echo
		when called by the shell.  Still works as usual if called
		by its normal name, for all you glob addicts.
	5) Spaces and newlines are no longer stripped from globbed lists.
	6) The -v flag has been enabled during sh -c parsing.  Since the shell
		processes `command` by doing an internal sh -c, `command`
		will be echoed twice if -v is set.
	7) Problems with access modes of .profile are fixed.
	8) Automatic exec is no longer default.
	8) Sub-shells no longer ignore SIGTERM.
	9) Globs and `commands` evaluated by background shells are no longer
		vulnerable to SIGINT.
	10) { command_list } may contain newlines.
	11) for i in * now gets all files in current directory.
	12) -u option gives error when positional parameter is unset.
	13) `pwd`/. no longer inserts space after `pwd`.
	14) -e option now aborts on evaluation errors and non-zero status.

New shell of 21 April:
	1) Files from 3 to NUFILE are no longer closed on entry.
	2) Glob stats matched paths to guarantee their existence.

Fixes in shell of 22.Apr.82:
	1) johann's pipe bug.
	2) no more blank commands.
	3) export and readonly can initialize values.
	4) $SHELL no longer exists.
	5) $VERSION does exist, gives date of source.
	6) $LASTERROR is automatic export.
	7) Incomplete pipelines, logical ands/ors prompt for rest of command.
	8) Redirection of control structures.
April 29, 1982
	1) `( command )' in middle of arglist gives syntax error instead
		of failed assertion message.
	2) LASTERROR no longer filled with garbage when null command
		causes error.
	3) The . command was leaving an open file descriptor; no more.
Shell of May 11, 1982:
	1) Problem with secondary prompt after missing `"' fixed.
	2) Glob made internal to shell.
	3) -x flag nul byte eliminated.
	4) -i flag now acts interactive even to pipes.
	5) attempted named pipes, but gave up.
May 26, 1982 shell:
	1) The exit status of `/bin/true' is now zero, rather than the status
	of the previous command executed.
	2) Interrupts of programs which catch interrupts are no longer missed
	by the shell.
	3) Shell command file stream is not closed when going to new command.
Shell of Aug 5, 1982:
	1) Interrupted command files now quit.
	2) All files used by shell are closed, all fd's can be redirected.
	3) Here documents can be interrupted.
	4) Rico's foobar offset bug -- caused by taking return status too
		seriously.
	5) Arguments preserved over flag resetting calls to `set'.
	6) ( ... ) arg arg now gives syntax error.
	7) Command file with nothing but escaped newlines can be executed.
	8) for i; do; done will not execute if null command list.
Shell of Oct 20, 1982
	1) Increased levels of pushdown for token recognition.
Shell of Nov 3, 1982
	1) Made traps reset when taken as in signal.
	2) Cleaned up arguments in multiple execs.
Shell of Feb 11, 1983
	1) Cleaned up the args given to set.
Shell of Oct 18, 1983
	1) Instituted "exec failed" message for SIGSYS with no core dump.
	2) Instituted . of /etc/profile on login.
Shell of May 29, 1984
	1) Modified var.c to slightly alter the handling of "LASTERROR".
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Commodore CBM-900

⟦86ce9a48e⟧ TextFile

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