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61d9bca581
Continuing alias substitution after 'command' (due to the final
space in the alias) is inherently broken and doing so by default is
incompatible with the POSIX standard, as aliases may contain
arbitrary shell grammar.
For instance, until the previous commit, the POSIX standard 'times'
command was an alias: times='{ { time;} 2>&1;}' -- and so, of
course, 'command times' gave a syntax error, although this is
a perfectly valid POSIX idiom that must be supported.
'command' is specified by POSIX as a regular builtin, not an alias.
Therefore it should always bypass aliases just as it bypasses
functions to expose standard builtin and external commands.
I can only imagine that the reason for this command='command '
alias was that some standard commands themselves were implemented
as aliases, and POSIX requires that standard commands are
accessible with the 'command' prefix. But implementing standard
commands as aliases is itself inherently broken. It never worked
for 'command times', as shown; and in any case, removing all
aliases with 'unalias -a' should not get rid of standard commands.
Similarly, the default alias nohup='nohup ' is also harmful.
Anyone who really wants to keep this behaviour can just define
these aliases themselves in their script or ~/.kshrc file.
src/cmd/ksh93/data/aliases.c:
- Remove default alias command='command '.
- Remove default alias nohup='nohup '.
src/cmd/ksh93/sh.1
- Remove the above default aliases from the list.
- Mention that the 'command' builtin does not search for aliases.
(cherry picked from commit 5cfe7c4e2015b7445da24983af5008035c4b6e1e)
162 lines
6.8 KiB
Text
162 lines
6.8 KiB
Text
This documents significant changes in the 93u+m branch of AT&T ksh93.
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For full details, see the git log at:
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https://github.com/modernish/ksh
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Any uppercase BUG_* names are modernish shell bug IDs.
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2020-06-06:
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- The 'times' command is now a builtin command that conforms to POSIX
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instead of an alias for the 'time' command. It displays the accumulated
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user and system CPU times, one line with the times used by the shell and
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another with those used by all of the shell's child processes.
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https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_27
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- The default aliases command='command ' and nohup='nohup ' have been
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removed because they caused breakage in an attempt to circumvent other
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breakage which is being fixed. In the unlikely even that anyone still
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needs alias substitution to continue on the command argument following
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'command' or 'nohup', it's easy to set these aliases yourself.
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2020-06-05:
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- Fix a bug that caused special variables such as PATH, LANG, LC_ALL,
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etc. to lose their effect after being unset in a subshell. For example:
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(unset PATH; PATH=/dev/null; ls); : wrongly ran 'ls'
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(unset LC_ALL; LC_ALL=badlocale); : failed to print a diagnostic
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- Fix crashes on some systems, including at least a crash in 'print -v' on
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macOS, by eliminating an invalid/undefined use of memccpy() on overlapping
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buffers in the commonly used sfputr() function.
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- Fix the ${.sh.subshell} level counter; it is no longer reset to zero when a
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non-forked subshell happens to fork into a separate process for some reason
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(an internal implementation detail that should be unnoticeable to scripts).
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2020-06-04:
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- Fix BUG_KBGPID: the $! special parameter was not set if a background job
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(somecommand &) or co-process (somecommand |&) was launched as the only
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command within a braces block with an attached redirection, for example:
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{
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somecommand &
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} >&2
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With the bug, $! was unchanged; now it contains the PID of somecommand.
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2020-05-31:
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- Fix a bug in autoloading functions. Directories in the path search list
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which should be skipped (e.g. because they don't exist) did not interact
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correctly with autoloaded functions, so that a function to autoload was
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not always found correctly.
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Details: https://github.com/att/ast/issues/1454
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2020-05-30:
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- Fix POSIX compliance of 'test'/'[' exit status on error. The command now
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returns status 2 instead of 1 when given an invalid number or arithmetic
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expression, e.g.:
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[ 123 -eq 123x ]; echo $?
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now outputs 2 instead of 1.
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2020-05-29:
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- Fix BUG_FNSUBSH: functions can now be correctly redefined and unset in
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subshell environments (such as ( ... ), $(command substitutions), etc).
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Before this fix, this was silently ignored, causing the function by the
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same name from the parent shell environment to be executed instead.
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fn() { echo mainsh; }
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(fn() { echo subsh; }; fn); fn
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This now correctly outputs "subsh mainsh" instead of "mainsh mainsh".
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ls() { echo "ls executed"; }
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(unset -f ls; ls); ls
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This now correctly lists your directory and then prints "ls executed",
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instead of printing "ls executed" twice.
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- Fix a similar bug with aliases. These can now be correctly unset
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in subshell environments.
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2020-05-21:
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- Fix truncating of files with the combined redirections '<>;file' and
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'<#pattern'. The bug was caused by out-of-sync streams.
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Details and discussion: https://github.com/att/ast/issues/61
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- Patched code injection vulnerability CVE-2019-14868. As a result, you can
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no longer use expressions in imported numeric environment variables; only
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integer literals are allowed.
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2020-05-20:
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- Fix BUG_ISSETLOOP. Expansions like ${var+set} remained static when used
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within a 'for', 'while' or 'until' loop; the expansions din't change along
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with the state of the variable, so they could not be used to check whether a
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variable is set within a loop if the state of that variable changed in the
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course of the loop.
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- Fix BUG_IFSISSET. ${IFS+s} always yielded 's', and [[ -v IFS ]] always
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yielded true, even if IFS is unset. This applied to IFS only.
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2020-05-19:
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- Fix 'command -p'. The -p option causes the operating system's standard
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utilities path (as output by 'getconf PATH') to be searched instead of $PATH.
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Before this fix, this was broken on non-interactive shells as the internal
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variable holding the default PATH value was not correctly initialised.
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2020-05-16:
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- Fix 'test -t 1', '[ -t 1 ]', '[[ -t 1 ]]' in command substitutions.
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Standard output (file descriptor 1) tested as being on a terminal within a
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command substitution, which makes no sense as the command substitution is
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supposed to be catching standard output.
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v=$(echo begincomsub
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[ -t 1 ] && echo oops
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echo endcomsub)
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echo "$v"
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This now does not output "oops".
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2020-05-14:
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- Fix syncing history when print -s -f is used. For example, the
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following now correctly adds a 'cd' command to the history:
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print -s -f 'cd -- %q\n' "$PWD"
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Ref.: https://github.com/att/ast/issues/425
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https://github.com/att/ast/pull/442
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- Fix BUG_PUTIOERR: Output builtins now correctly detect and report
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input/output errors. This allows scripts to check for a nonzero exit
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status on the 'print', 'printf' and 'echo' builtins and prevent possible
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infinite loops if SIGPIPE is ignored.
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- Add a convenient bin/run_ksh_tests script to the source tree that
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sets up the necessary environment and runs the ksh regression tests.
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2020-05-13:
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- Fix BUG_CASELIT: an undocumented 'case' pattern matching misbehaviour that
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goes back to the original Bourne shell, but wasn't discovered until 2018.
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If a pattern doesn't match as a pattern, it was tried again as a literal
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string. This broke common validation use cases, e.g.:
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n='[0-9]'
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case $n in
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( [0-9] ) echo "$n is a number" ;;
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esac
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would output "[0-9] is a number" as the literal string fallback matches the
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pattern. As this misbehaviour was never documented anywhere (not for Bourne,
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ksh88, or ksh93), and it was never replicated in other shells (not even in
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ksh88 clones pdksh and mksh), it is unlikely any scripts rely on it.
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Of course, a literal string fallback, should it be needed, is trivial to
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implement correctly without this breakage:
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case $n in
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( [0-9] | "[0-9]") echo "$n is a number or the number pattern" ;;
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esac
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Ref.: https://github.com/att/ast/issues/476
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- Fix BUG_REDIRIO: ksh used to redirect standard output by default when no
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file descriptor was specified with the rarely used '<>' reading/writing
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redirection operator. It now redirects standard input by default, as POSIX
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specifies and as all other POSIX shells do. To redirect standard output
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for reading and writing, you now need '1<>'.
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Ref.: https://github.com/att/ast/issues/75
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http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_07_07
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