Imported from ../bash-3.1.tar.gz.

1 files changed, 61 insertions, 34 deletions

diff --git a/POSIX b/POSIX
index 05700c61..f8c983ea 100644
--- a/POSIX
+++ b/POSIX
@@ -1,5 +1,5 @@
-Bash POSIX Mode
-===============
+6.11 Bash POSIX Mode
+====================
 
 Starting Bash with the `--posix' command-line option or executing `set
 -o posix' while Bash is running will cause Bash to conform more closely
@@ -22,58 +22,59 @@ The following list is what's changed when `POSIX mode' is in effect:
      is stopped is `Stopped(SIGNAME)', where SIGNAME is, for example,
      `SIGTSTP'.
 
-  4. Reserved words may not be aliased.
+  4. 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.
 
-  5. The POSIX 1003.2 `PS1' and `PS2' expansions of `!' to the history
+  5. Reserved words appearing in a context where reserved words are
+     recognized do not undergo alias expansion.
+
+  6. The POSIX 1003.2 `PS1' and `PS2' expansions of `!' to the history
      number and `!!' to `!' are enabled, and parameter expansion is
      performed on the values of `PS1' and `PS2' regardless of the
      setting of the `promptvars' option.
 
-  6. The POSIX 1003.2 startup files are executed (`$ENV') rather than
+  7. The POSIX 1003.2 startup files are executed (`$ENV') rather than
      the normal Bash files.
 
-  7. Tilde expansion is only performed on assignments preceding a
+  8. Tilde expansion is only performed on assignments preceding a
      command name, rather than on all assignment statements on the line.
 
-  8. The default history file is `~/.sh_history' (this is the default
+  9. The default history file is `~/.sh_history' (this is the default
      value of `$HISTFILE').
 
-  9. The output of `kill -l' prints all the signal names on a single
+ 10. The output of `kill -l' prints all the signal names on a single
      line, separated by spaces, without the `SIG' prefix.
 
- 10. The `kill' builtin does not accept signal names with a `SIG'
+ 11. The `kill' builtin does not accept signal names with a `SIG'
      prefix.
 
- 11. Non-interactive shells exit if FILENAME in `.' FILENAME is not
+ 12. Non-interactive shells exit if FILENAME in `.' FILENAME is not
      found.
 
- 12. Non-interactive shells exit if a syntax error in an arithmetic
+ 13. Non-interactive shells exit if a syntax error in an arithmetic
      expansion results in an invalid expression.
 
- 13. Redirection operators do not perform filename expansion on the word
+ 14. Redirection operators do not perform filename expansion on the word
      in the redirection unless the shell is interactive.
 
- 14. Redirection operators do not perform word splitting on the word in
+ 15. Redirection operators do not perform word splitting on the word in
      the redirection.
 
- 15. Function names must be valid shell `name's.  That is, they may not
+ 16. Function names must be valid shell `name's.  That is, they may not
      contain characters other than letters, digits, and underscores, and
      may not start with a digit.  Declaring a function with an invalid
      name causes a fatal syntax error in non-interactive shells.
 
- 16. POSIX 1003.2 `special' builtins are found before shell functions
+ 17. POSIX 1003.2 special builtins are found before shell functions
      during command lookup.
 
- 17. If a POSIX 1003.2 special builtin returns an error status, a
+ 18. If a POSIX 1003.2 special builtin returns an error status, a
      non-interactive shell exits.  The fatal errors are those listed in
      the POSIX.2 standard, and include things like passing incorrect
      options, redirection errors, variable assignment errors for
      assignments preceding the command name, and so on.
 
- 18. If the `cd' builtin finds a directory to change to using
-     `$CDPATH', the value it assigns to the `PWD' variable does not
-     contain any symbolic links, as if `cd -P' had been executed.
-
  19. If `CDPATH' is set, the `cd' builtin will not implicitly append
      the current directory to it.  This means that `cd' will fail if no
      valid directory name can be constructed from any of the entries in
@@ -105,9 +106,10 @@ The following list is what's changed when `POSIX mode' is in effect:
 
  27. 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.  If users want to reset the handler for a
-     given signal to the original disposition, they should use `-' as
-     the first argument.
+     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.
 
  28. The `.' and `source' builtins do not search the current directory
      for the filename argument if it is not found by searching `PATH'.
@@ -134,19 +136,44 @@ The following list is what's changed when `POSIX mode' is in effect:
      argument does not refer to an existing directory, `cd' will fail
      instead of falling back to PHYSICAL mode.
 
-There is other POSIX 1003.2 behavior that Bash does not implement.
-Specifically:
+ 35. When the `pwd' builtin is supplied the `-P' option, it resets
+     `$PWD' to a pathname containing no symlinks.
+
+ 36. The `pwd' builtin verifies that the value it prints is the same as
+     the current directory, even if it is not asked to check the file
+     system with the `-P' option.
+
+ 37. When listing the history, the `fc' builtin does not include an
+     indication of whether or not a history entry has been modified.
+
+ 38. The default editor used by `fc' is `ed'.
+
+ 39. The `type' and `command' builtins will not report a non-executable
+     file as having been found, though the shell will attempt to
+     execute such a file if it is the only so-named file found in
+     `$PATH'.
+
+ 40. The `vi' editing mode will invoke the `vi' editor directly when
+     the `v' command is run, instead of checking `$FCEDIT' and
+     `$EDITOR'.
+
+ 41. 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.
+
+
+There is other POSIX 1003.2 behavior that Bash does not implement by
+default even when in POSIX mode.  Specifically:
 
-  1. Assignment statements affect the execution environment of all
-     builtins, not just special ones.
+  1. The `fc' builtin checks `$EDITOR' as a program to edit history
+     entries if `FCEDIT' is unset, rather than defaulting directly to
+     `ed'.  `fc' uses `ed' if `EDITOR' is unset.
 
-  2. When a subshell is created to execute a shell script with execute
-     permission, but without a leading `#!', Bash sets `$0' to the full
-     pathname of the script as found by searching `$PATH', rather than
-     the command as typed by the user.
+  2. As noted above, Bash requires the `xpg_echo' option to be enabled
+     for the `echo' builtin to be fully conformant.
 
-  3. When using `.' to source a shell script found in `$PATH', bash
-     checks execute permission bits rather than read permission bits,
-     just as if it were searching for a command.
 
+Bash can be configured to be POSIX-conformant by default, by specifying
+the `--enable-strict-posix-default' to `configure' when building (*note
+Optional Features::).