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@@ -58,158 +58,165 @@ The following list is what's changed when 'POSIX mode' is in effect:
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14. POSIX special builtins are found before shell functions during
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command lookup.
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15. Literal tildes that appear as the first character in elements of
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15. When printing shell function definitions (e.g., by 'type'), Bash
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does not print the 'function' keyword.
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16. Literal tildes that appear as the first character in elements of
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the 'PATH' variable are not expanded as described above under *note
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Tilde Expansion::.
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16. The 'time' reserved word may be used by itself as a command. When
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17. The 'time' reserved word may be used by itself as a command. When
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used in this way, it displays timing statistics for the shell and
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its completed children. The 'TIMEFORMAT' variable controls the
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format of the timing information.
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17. When parsing and expanding a ${...} expansion that appears within
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18. When parsing and expanding a ${...} expansion that appears within
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double quotes, single quotes are no longer special and cannot be
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used to quote a closing brace or other special character, unless
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the operator is one of those defined to perform pattern removal.
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In this case, they do not have to appear as matched pairs.
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18. The parser does not recognize 'time' as a reserved word if the
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19. The parser does not recognize 'time' as a reserved word if the
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next token begins with a '-'.
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19. The '!' character does not introduce history expansion within a
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20. The '!' character does not introduce history expansion within a
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double-quoted string, even if the 'histexpand' option is enabled.
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20. If a POSIX special builtin returns an error status, a
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21. If a POSIX special builtin returns an error status, a
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non-interactive shell exits. The fatal errors are those listed in
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the POSIX standard, and include things like passing incorrect
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options, redirection errors, variable assignment errors for
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assignments preceding the command name, and so on.
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21. A non-interactive shell exits with an error status if a variable
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22. A non-interactive shell exits with an error status if a variable
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assignment error occurs when no command name follows the assignment
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statements. A variable assignment error occurs, for example, when
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trying to assign a value to a readonly variable.
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22. A non-interactive shell exits with an error status if a variable
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23. A non-interactive shell exits with an error status if a variable
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assignment error occurs in an assignment statement preceding a
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special builtin, but not with any other simple command.
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23. A non-interactive shell exits with an error status if the
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24. A non-interactive shell exits with an error status if the
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iteration variable in a 'for' statement or the selection variable
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in a 'select' statement is a readonly variable.
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24. Non-interactive shells exit if FILENAME in '.' FILENAME is not
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25. Non-interactive shells exit if FILENAME in '.' FILENAME is not
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found.
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25. Non-interactive shells exit if a syntax error in an arithmetic
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26. Non-interactive shells exit if a syntax error in an arithmetic
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expansion results in an invalid expression.
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26. Non-interactive shells exit on word expansion errors.
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27. Non-interactive shells exit if a parameter expansion error occurs.
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27. Non-interactive shells exit if there is a syntax error in a script
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28. Non-interactive shells exit if there is a syntax error in a script
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read with the '.' or 'source' builtins, or in a string processed by
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the 'eval' builtin.
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28. Process substitution is not available.
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29. Process substitution is not available.
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29. While variable indirection is available, it may not be applied to
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30. While variable indirection is available, it may not be applied to
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the '#' and '?' special parameters.
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30. Assignment statements preceding POSIX special builtins persist in
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31. When expanding the '*' special parameter in a pattern context
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where the expansion is double-quoted does not treat the '$*' as if
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it were double-quoted.
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32. Assignment statements preceding POSIX special builtins persist in
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the shell environment after the builtin completes.
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31. Assignment statements preceding shell function calls persist in
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33. Assignment statements preceding shell function calls persist in
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the shell environment after the function returns, as if a POSIX
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special builtin command had been executed.
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32. The 'command' builtin does not prevent builtins that take
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34. The 'command' builtin does not prevent builtins that take
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assignment statements as arguments from expanding them as
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assignment statements; when not in POSIX mode, assignment builtins
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lose their assignment statement expansion properties when preceded
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by 'command'.
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33. The 'bg' builtin uses the required format to describe each job
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35. The 'bg' builtin uses the required format to describe each job
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placed in the background, which does not include an indication of
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whether the job is the current or previous job.
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34. The output of 'kill -l' prints all the signal names on a single
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36. The output of 'kill -l' prints all the signal names on a single
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line, separated by spaces, without the 'SIG' prefix.
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35. The 'kill' builtin does not accept signal names with a 'SIG'
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37. The 'kill' builtin does not accept signal names with a 'SIG'
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prefix.
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36. The 'export' and 'readonly' builtin commands display their output
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38. The 'export' and 'readonly' builtin commands display their output
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in the format required by POSIX.
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37. The 'trap' builtin displays signal names without the leading
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39. The 'trap' builtin displays signal names without the leading
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'SIG'.
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38. The 'trap' builtin doesn't check the first argument for a possible
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40. The 'trap' builtin doesn't check the first argument for a possible
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signal specification and revert the signal handling to the original
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disposition if it is, unless that argument consists solely of
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digits and is a valid signal number. If users want to reset the
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handler for a given signal to the original disposition, they should
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use '-' as the first argument.
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39. The '.' and 'source' builtins do not search the current directory
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41. The '.' and 'source' builtins do not search the current directory
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for the filename argument if it is not found by searching 'PATH'.
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40. Enabling POSIX mode has the effect of setting the
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42. Enabling POSIX mode has the effect of setting the
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'inherit_errexit' option, so subshells spawned to execute command
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substitutions inherit the value of the '-e' option from the parent
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shell. When the 'inherit_errexit' option is not enabled, Bash
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clears the '-e' option in such subshells.
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41. When the 'alias' builtin displays alias definitions, it does not
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43. When the 'alias' builtin displays alias definitions, it does not
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display them with a leading 'alias ' unless the '-p' option is
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supplied.
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42. When the 'set' builtin is invoked without options, it does not
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44. When the 'set' builtin is invoked without options, it does not
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display shell function names and definitions.
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43. When the 'set' builtin is invoked without options, it displays
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45. When the 'set' builtin is invoked without options, it displays
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variable values without quotes, unless they contain shell
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metacharacters, even if the result contains nonprinting characters.
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44. When the 'cd' builtin is invoked in LOGICAL mode, and the pathname
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46. When the 'cd' builtin is invoked in LOGICAL mode, and the pathname
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constructed from '$PWD' and the directory name supplied as an
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argument does not refer to an existing directory, 'cd' will fail
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instead of falling back to PHYSICAL mode.
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45. The 'pwd' builtin verifies that the value it prints is the same as
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47. The 'pwd' builtin verifies that the value it prints is the same as
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the current directory, even if it is not asked to check the file
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system with the '-P' option.
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46. When listing the history, the 'fc' builtin does not include an
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48. When listing the history, the 'fc' builtin does not include an
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indication of whether or not a history entry has been modified.
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47. The default editor used by 'fc' is 'ed'.
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49. The default editor used by 'fc' is 'ed'.
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48. The 'type' and 'command' builtins will not report a non-executable
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50. The 'type' and 'command' builtins will not report a non-executable
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file as having been found, though the shell will attempt to execute
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such a file if it is the only so-named file found in '$PATH'.
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49. The 'vi' editing mode will invoke the 'vi' editor directly when
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51. The 'vi' editing mode will invoke the 'vi' editor directly when
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the 'v' command is run, instead of checking '$VISUAL' and
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'$EDITOR'.
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50. When the 'xpg_echo' option is enabled, Bash does not attempt to
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52. When the 'xpg_echo' option is enabled, Bash does not attempt to
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interpret any arguments to 'echo' as options. Each argument is
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displayed, after escape characters are converted.
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51. The 'ulimit' builtin uses a block size of 512 bytes for the '-c'
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53. The 'ulimit' builtin uses a block size of 512 bytes for the '-c'
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and '-f' options.
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52. The arrival of 'SIGCHLD' when a trap is set on 'SIGCHLD' does not
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54. The arrival of 'SIGCHLD' when a trap is set on 'SIGCHLD' does not
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interrupt the 'wait' builtin and cause it to return immediately.
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The trap command is run once for each child that exits.
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53. The 'read' builtin may be interrupted by a signal for which a trap
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55. The 'read' builtin may be interrupted by a signal for which a trap
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has been set. If Bash receives a trapped signal while executing
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'read', the trap handler executes and 'read' returns an exit status
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greater than 128.
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54. Bash removes an exited background process's status from the list
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56. Bash removes an exited background process's status from the list
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of such statuses after the 'wait' builtin is used to obtain it.
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There is other POSIX behavior that Bash does not implement by default
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