Process substitution is disabled in POSIX mode. A 'git blame' on parse.y
suggests that this has been the case since bash prehistory.
To me, this seems:
- Inconsistent. Other bash extensions are not disabled when POSIX mode
is active; as far as I can tell, this is the only one.
- Unnecessary. The <(...) and >(...) syntax is a straightforward syntax
error in POSIX, so it's not as if this particular extension somehow
conflicts with POSIX standard scripts.
- Annoying. When a bash-specific script uses functions written for POSIX
(such as the modernish library), it needs to run in POSIX mode for
compatibility with those, but can still use every bash extension
except this one. It just seems pointless.
Would you consider the attached patch, which removes this limitation?
Thanks,
- M.
--
modernish -- harness the shell
https://github.com/modernish/modernish
diff --git a/POSIX b/POSIX
index f3f4a0b7..d2836070 100644
--- a/POSIX
+++ b/POSIX
@@ -115,120 +115,118 @@ The following list is what's changed when 'POSIX mode'
is in effect:
read with the '.' or 'source' builtins, or in a string processed by
the 'eval' builtin.
- 30. Process substitution is not available.
-
- 31. While variable indirection is available, it may not be applied to
+ 30. While variable indirection is available, it may not be applied to
the '#' and '?' special parameters.
- 32. When expanding the '*' special parameter in a pattern context
+ 31. When expanding the '*' special parameter in a pattern context
where the expansion is double-quoted does not treat the '$*' as if
it were double-quoted.
- 33. Assignment statements preceding POSIX special builtins persist in
+ 32. Assignment statements preceding POSIX special builtins persist in
the shell environment after the builtin completes.
- 34. Assignment statements preceding shell function calls persist in
+ 33. Assignment statements preceding shell function calls persist in
the shell environment after the function returns, as if a POSIX
special builtin command had been executed.
- 35. The 'command' builtin does not prevent builtins that take
+ 34. The 'command' builtin does not prevent builtins that take
assignment statements as arguments from expanding them as
assignment statements; when not in POSIX mode, assignment builtins
lose their assignment statement expansion properties when preceded
by 'command'.
- 36. The 'bg' builtin uses the required format to describe each job
+ 35. The 'bg' builtin uses the required format to describe each job
placed in the background, which does not include an indication of
whether the job is the current or previous job.
- 37. The output of 'kill -l' prints all the signal names on a single
+ 36. The output of 'kill -l' prints all the signal names on a single
line, separated by spaces, without the 'SIG' prefix.
- 38. The 'kill' builtin does not accept signal names with a 'SIG'
+ 37. The 'kill' builtin does not accept signal names with a 'SIG'
prefix.
- 39. The 'export' and 'readonly' builtin commands display their output
+ 38. The 'export' and 'readonly' builtin commands display their output
in the format required by POSIX.
- 40. The 'trap' builtin displays signal names without the leading
+ 39. The 'trap' builtin displays signal names without the leading
'SIG'.
- 41. The 'trap' builtin doesn't check the first argument for a possible
+ 40. The 'trap' builtin doesn't check the first argument for a possible
signal specification and revert the signal handling to the original
disposition if it is, unless that argument consists solely of
digits and is a valid signal number. If users want to reset the
handler for a given signal to the original disposition, they should
use '-' as the first argument.
- 42. The '.' and 'source' builtins do not search the current directory
+ 41. The '.' and 'source' builtins do not search the current directory
for the filename argument if it is not found by searching 'PATH'.
- 43. Enabling POSIX mode has the effect of setting the
+ 42. Enabling POSIX mode has the effect of setting the
'inherit_errexit' option, so subshells spawned to execute command
substitutions inherit the value of the '-e' option from the parent
shell. When the 'inherit_errexit' option is not enabled, Bash
clears the '-e' option in such subshells.
- 44. Enabling POSIX mode has the effect of setting the 'shift_verbose'
+ 43. Enabling POSIX mode has the effect of setting the 'shift_verbose'
option, so numeric arguments to 'shift' that exceed the number of
positional parameters will result in an error message.
- 45. When the 'alias' builtin displays alias definitions, it does not
+ 44. When the 'alias' builtin displays alias definitions, it does not
display them with a leading 'alias ' unless the '-p' option is
supplied.
- 46. When the 'set' builtin is invoked without options, it does not
+ 45. When the 'set' builtin is invoked without options, it does not
display shell function names and definitions.
- 47. When the 'set' builtin is invoked without options, it displays
+ 46. When the 'set' builtin is invoked without options, it displays
variable values without quotes, unless they contain shell
metacharacters, even if the result contains nonprinting characters.
- 48. When the 'cd' builtin is invoked in LOGICAL mode, and the pathname
+ 47. When the 'cd' builtin is invoked in LOGICAL mode, and the pathname
constructed from '$PWD' and the directory name supplied as an
argument does not refer to an existing directory, 'cd' will fail
instead of falling back to PHYSICAL mode.
- 49. When the 'cd' builtin cannot change a directory because the length
+ 48. When the 'cd' builtin cannot change a directory because the length
of the pathname constructed from '$PWD' and the directory name
supplied as an argument exceeds PATH_MAX when all symbolic links
are expanded, 'cd' will fail instead of attempting to use only the
supplied directory name.
- 50. The 'pwd' builtin verifies that the value it prints is the same as
+ 49. The 'pwd' builtin verifies that the value it prints is the same as
the current directory, even if it is not asked to check the file
system with the '-P' option.
- 51. When listing the history, the 'fc' builtin does not include an
+ 50. When listing the history, the 'fc' builtin does not include an
indication of whether or not a history entry has been modified.
- 52. The default editor used by 'fc' is 'ed'.
+ 51. The default editor used by 'fc' is 'ed'.
- 53. The 'type' and 'command' builtins will not report a non-executable
+ 52. The 'type' and 'command' builtins will not report a non-executable
file as having been found, though the shell will attempt to execute
such a file if it is the only so-named file found in '$PATH'.
- 54. The 'vi' editing mode will invoke the 'vi' editor directly when
+ 53. The 'vi' editing mode will invoke the 'vi' editor directly when
the 'v' command is run, instead of checking '$VISUAL' and
'$EDITOR'.
- 55. When the 'xpg_echo' option is enabled, Bash does not attempt to
+ 54. When the 'xpg_echo' option is enabled, Bash does not attempt to
interpret any arguments to 'echo' as options. Each argument is
displayed, after escape characters are converted.
- 56. The 'ulimit' builtin uses a block size of 512 bytes for the '-c'
+ 55. The 'ulimit' builtin uses a block size of 512 bytes for the '-c'
and '-f' options.
- 57. The arrival of 'SIGCHLD' when a trap is set on 'SIGCHLD' does not
+ 56. The arrival of 'SIGCHLD' when a trap is set on 'SIGCHLD' does not
interrupt the 'wait' builtin and cause it to return immediately.
The trap command is run once for each child that exits.
- 58. The 'read' builtin may be interrupted by a signal for which a trap
+ 57. The 'read' builtin may be interrupted by a signal for which a trap
has been set. If Bash receives a trapped signal while executing
'read', the trap handler executes and 'read' returns an exit status
greater than 128.
- 59. Bash removes an exited background process's status from the list
+ 58. Bash removes an exited background process's status from the list
of such statuses after the 'wait' builtin is used to obtain it.
There is other POSIX behavior that Bash does not implement by default
diff --git a/parse.y b/parse.y
index 35a78aa0..51794c2d 100644
--- a/parse.y
+++ b/parse.y
@@ -3460,9 +3460,8 @@ itrace("shell_getc: bash_input.location.string = `%s'",
bash_input.location.stri
parser_state &= ~PST_SUBSHELL;
#if defined (PROCESS_SUBSTITUTION)
- /* Check for the constructs which introduce process substitution.
- Shells running in `posix mode' don't do process substitution. */
- if MBTEST(posixly_correct || ((character != '>' && character != '<') ||
peek_char != '(')) /*)*/
+ /* Check for the constructs which introduce process substitution. */
+ if MBTEST((character != '>' && character != '<') || peek_char != '(')
/*)*/
#endif /* PROCESS_SUBSTITUTION */
return (character);
}
diff --git a/subst.c b/subst.c
index 6c5b32c1..716011a0 100644
--- a/subst.c
+++ b/subst.c
@@ -10046,7 +10046,7 @@ add_string:
{
/* XXX - technically this should only be expanded at the start
of a word */
- if (string[++sindex] != LPAREN || (quoted &
(Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) || (word->flags & (W_DQUOTE|W_NOPROCSUB)) ||
posixly_correct)
+ if (string[++sindex] != LPAREN || (quoted &
(Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) || (word->flags & (W_DQUOTE|W_NOPROCSUB)))
{
sindex--; /* add_character: label increments sindex */
goto add_character;
