1026006db3
The $! special parameter was not set if a background job
(somecommand &) or co-process (somecommand |&) was launched as the
only command within a braces block with an attached redirection,
for example:
{
somecommand &
} >&2
With the bug, $! was unchanged; now it contains the PID of
somecommand.
Ref.: https://github.com/att/ast/issues/1357
src/cmd/ksh93/sh/parse.c: item():
- When processing redirections following a compound command, always
create a parent node with the TSETIO (I/O redirection) token.
Before this commit, if the last command was of type TFORK (and
the last command only tested as TFORK if the bg job or coprocess
was the only command in a braces block, because the ksh parser
optimises away the braces in that case), then the parent node was
created with the TFORK token instead.
I have no idea what David Korn's intention was with that, but
this is clearly very wrong. Creating another TFORK node when
parsing the redirection caused sh_exec() in sh/xec.c to execute
the redirection in an extra forked, non-background subshell.
Since redirections are executed before anything else, this
subshell is what then launched the background job between the
braces, so $! (a.k.a. shp->bckpid) was updated in that subshell
only, and never in the main shell. The extra subshell also
prevented the background job from being noticed by job control
on interactive shells.
So, the fix is simply to remove the broken test for TFORK.
src/cmd/ksh93/tests/variables.sh:
- Add regression tests for a bg job and a co-process as the only
command within a braces block with attached redirection.
(cherry picked from commit ffe5df30e69f7b596941a98498014d8e838861f2)
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| TODO | ||
KornShell 93u+m
This repository is used to develop bugfixes to the last stable release (93u+ 2012-08-01) of ksh93, formerly developed by AT&T Software Technology (AST). The sources in this repository were forked from the Github AST repository which is no longer under active development.
To see what's fixed, see NEWS and click on commit messages for full details.
To see what's left to fix, see TODO.
Policy
- No new features. Bug fixes only.
- No major rewrites. No refactoring code that is not fully understood.
- No changes in documented behaviour, except if required for compliance with the POSIX shell language standard which David Korn intended for ksh to follow.
- No 100% bug compatibility. Broken and undocumented behaviour gets fixed.
- No bureaucracy, no formalities. Just fix it, or report it: create issues, send pull requests. Every interested party is invited to contribute.
- To help increase everyone's understanding of this code base, fixes and significant changes should be fully documented in commit messages.
Why?
Between 2017 and 2020 there was an ultimately unsuccessful attempt to breathe new life into the KornShell by extensively refactoring the last unstable AST beta version (93v-). While that ksh2020 branch is now abandoned and still has many critical bugs, it also had a lot of bugs fixed. More importantly, the AST issue tracker now contains a lot of documentation on how to fix those bugs, which makes it possible to backport many of them to the last stable release instead.
In February 2020, having concluded the AST 93v- beta was too broken to base new work on, others decided to start a new fork based on the last stable 93u+ 2012-08-01 release. Unfortunately, as of June 2020, the new ksh-community organisation is yet to see any significant activity four months after its bootstrapping. I hope that will change; I am ready to join efforts with them at any time, as well as anyone else who wants to contribute.
The last stable ksh93 release from 2012 is the least buggy release currently available, but it still has many serious bugs. So it is well past time to start fixing those bugs, leave the rest of the code alone, and get an improved release out there.
Build
After cloning this repo, cd to the top directory of it and run:
./bin/package make
If you have trouble or want to tune the binaries, you may pass additional compiler and linker flags by appending it to the command shown above. E.g.:
./bin/package make \
SHELL=/bin/bash CCFLAGS="-xc99 -D_XPG6 -m64 -xO4" LDFLAGS="-m64"
For more information run
bin/package help
Many other commands in this repo self-document via the --help, --man and
--html options; those that do have no separate manual page.
Test
After compiling, you can run the regression tests. Start by reading the information printed by:
./bin/shtests --man