mirror of
https://https.git.savannah.gnu.org/git/bash.git
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fix to multiple alias expansion problem in command substitutions
This commit is contained in:
Chet Ramey
+119
-112
@@ -2,12 +2,12 @@ This is bashref.info, produced by makeinfo version 6.8 from
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bashref.texi.
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This text is a brief description of the features that are present in the
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Bash shell (version 5.2, 17 January 2022).
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Bash shell (version 5.2, 1 February 2022).
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This is Edition 5.2, last updated 17 January 2022, of 'The GNU Bash
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This is Edition 5.2, last updated 1 February 2022, of 'The GNU Bash
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Reference Manual', for 'Bash', Version 5.2.
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Copyright (C) 1988-2021 Free Software Foundation, Inc.
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Copyright (C) 1988-2022 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this
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document under the terms of the GNU Free Documentation License,
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@@ -27,10 +27,10 @@ Bash Features
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*************
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This text is a brief description of the features that are present in the
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Bash shell (version 5.2, 17 January 2022). The Bash home page is
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Bash shell (version 5.2, 1 February 2022). The Bash home page is
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<http://www.gnu.org/software/bash/>.
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This is Edition 5.2, last updated 17 January 2022, of 'The GNU Bash
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This is Edition 5.2, last updated 1 February 2022, of 'The GNU Bash
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Reference Manual', for 'Bash', Version 5.2.
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Bash contains features that appear in other popular shells, and some
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@@ -7029,73 +7029,80 @@ startup files.
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7. Reserved words appearing in a context where reserved words are
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recognized do not undergo alias expansion.
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8. The POSIX 'PS1' and 'PS2' expansions of '!' to the history number
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8. Alias expansion is performed when initially parsing a command
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substitution. The default mode generally defers it, when enabled,
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until the command substitution is executed. This means that
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command substitution will not expand aliases that are defined after
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the command substitution is initially parsed (e.g., as part of a
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function definition).
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9. The POSIX 'PS1' and 'PS2' expansions of '!' to the history number
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and '!!' to '!' are enabled, and parameter expansion is performed
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on the values of 'PS1' and 'PS2' regardless of the setting of the
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'promptvars' option.
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9. The POSIX startup files are executed ('$ENV') rather than the
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10. The POSIX startup files are executed ('$ENV') rather than the
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normal Bash files.
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10. Tilde expansion is only performed on assignments preceding a
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11. Tilde expansion is only performed on assignments preceding a
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command name, rather than on all assignment statements on the line.
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11. The default history file is '~/.sh_history' (this is the default
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12. The default history file is '~/.sh_history' (this is the default
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value of '$HISTFILE').
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12. Redirection operators do not perform filename expansion on the
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13. Redirection operators do not perform filename expansion on the
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word in the redirection unless the shell is interactive.
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13. Redirection operators do not perform word splitting on the word in
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14. Redirection operators do not perform word splitting on the word in
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the redirection.
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14. Function names must be valid shell 'name's. That is, they may not
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15. Function names must be valid shell 'name's. That is, they may not
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contain characters other than letters, digits, and underscores, and
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may not start with a digit. Declaring a function with an invalid
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name causes a fatal syntax error in non-interactive shells.
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15. Function names may not be the same as one of the POSIX special
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16. Function names may not be the same as one of the POSIX special
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builtins.
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16. POSIX special builtins are found before shell functions during
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17. POSIX special builtins are found before shell functions during
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command lookup.
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17. When printing shell function definitions (e.g., by 'type'), Bash
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18. When printing shell function definitions (e.g., by 'type'), Bash
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does not print the 'function' keyword.
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18. Literal tildes that appear as the first character in elements of
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19. 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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19. The 'time' reserved word may be used by itself as a command. When
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20. 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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20. When parsing and expanding a ${...} expansion that appears within
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21. 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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21. The parser does not recognize 'time' as a reserved word if the
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22. 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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22. The '!' character does not introduce history expansion within a
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23. 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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23. If a POSIX special builtin returns an error status, a
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24. 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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24. A non-interactive shell exits with an error status if a variable
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25. 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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25. A non-interactive shell exits with an error status if a variable
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26. 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. For any
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other simple command, the shell aborts execution of that command,
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@@ -7103,133 +7110,133 @@ startup files.
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perform any further processing of the command in which the error
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occurred").
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26. A non-interactive shell exits with an error status if the
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27. 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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27. Non-interactive shells exit if FILENAME in '.' FILENAME is not
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28. Non-interactive shells exit if FILENAME in '.' FILENAME is not
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found.
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28. Non-interactive shells exit if a syntax error in an arithmetic
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29. 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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29. Non-interactive shells exit if a parameter expansion error occurs.
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30. Non-interactive shells exit if a parameter expansion error occurs.
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30. Non-interactive shells exit if there is a syntax error in a script
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31. 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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31. While variable indirection is available, it may not be applied to
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32. While variable indirection is available, it may not be applied to
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the '#' and '?' special parameters.
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32. When expanding the '*' special parameter in a pattern context
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33. 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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33. Assignment statements preceding POSIX special builtins persist in
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34. Assignment statements preceding POSIX special builtins persist in
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the shell environment after the builtin completes.
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34. The 'command' builtin does not prevent builtins that take
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35. 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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35. The 'bg' builtin uses the required format to describe each job
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36. 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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36. The output of 'kill -l' prints all the signal names on a single
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37. 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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37. The 'kill' builtin does not accept signal names with a 'SIG'
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38. The 'kill' builtin does not accept signal names with a 'SIG'
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prefix.
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38. The 'export' and 'readonly' builtin commands display their output
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39. The 'export' and 'readonly' builtin commands display their output
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in the format required by POSIX.
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39. The 'trap' builtin displays signal names without the leading
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40. The 'trap' builtin displays signal names without the leading
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'SIG'.
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40. The 'trap' builtin doesn't check the first argument for a possible
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41. 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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41. 'trap -p' displays signals whose dispositions are set to SIG_DFL
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42. 'trap -p' displays signals whose dispositions are set to SIG_DFL
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and those that were ignored when the shell started.
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42. The '.' and 'source' builtins do not search the current directory
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43. 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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43. Enabling POSIX mode has the effect of setting the
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44. 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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44. Enabling POSIX mode has the effect of setting the 'shift_verbose'
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45. Enabling POSIX mode has the effect of setting the 'shift_verbose'
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option, so numeric arguments to 'shift' that exceed the number of
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positional parameters will result in an error message.
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45. When the 'alias' builtin displays alias definitions, it does not
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46. 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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46. When the 'set' builtin is invoked without options, it does not
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47. 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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47. When the 'set' builtin is invoked without options, it displays
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48. 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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48. When the 'cd' builtin is invoked in logical mode, and the pathname
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49. When the 'cd' builtin is invoked in logical mode, and the pathname
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constructed from '$PWD' and the directory name supplied as an
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argument does not refer to an existing directory, 'cd' will fail
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instead of falling back to physical mode.
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49. When the 'cd' builtin cannot change a directory because the length
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50. When the 'cd' builtin cannot change a directory because the length
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of the pathname constructed from '$PWD' and the directory name
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supplied as an argument exceeds 'PATH_MAX' when all symbolic links
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are expanded, 'cd' will fail instead of attempting to use only the
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supplied directory name.
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50. The 'pwd' builtin verifies that the value it prints is the same as
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51. 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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51. When listing the history, the 'fc' builtin does not include an
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52. 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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52. The default editor used by 'fc' is 'ed'.
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53. The default editor used by 'fc' is 'ed'.
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53. The 'type' and 'command' builtins will not report a non-executable
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54. 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 '$PATH'.
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54. The 'vi' editing mode will invoke the 'vi' editor directly when
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55. The 'vi' editing mode will invoke the 'vi' editor directly when
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the 'v' command is run, instead of checking '$VISUAL' and
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'$EDITOR'.
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55. When the 'xpg_echo' option is enabled, Bash does not attempt to
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56. 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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56. The 'ulimit' builtin uses a block size of 512 bytes for the '-c'
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57. The 'ulimit' builtin uses a block size of 512 bytes for the '-c'
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and '-f' options.
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57. The arrival of 'SIGCHLD' when a trap is set on 'SIGCHLD' does not
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58. 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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58. The 'read' builtin may be interrupted by a signal for which a trap
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59. 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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59. Bash removes an exited background process's status from the list
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60. 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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@@ -12520,61 +12527,61 @@ Node: Directory Stack Builtins288792
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Node: Controlling the Prompt293052
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Node: The Restricted Shell296017
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Node: Bash POSIX Mode298627
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Node: Shell Compatibility Mode309900
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Node: Job Control317929
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Node: Job Control Basics318389
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Node: Job Control Builtins323391
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Node: Job Control Variables328791
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Node: Command Line Editing329947
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Node: Introduction and Notation331618
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Node: Readline Interaction333241
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Node: Readline Bare Essentials334432
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Node: Readline Movement Commands336215
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Node: Readline Killing Commands337175
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Node: Readline Arguments339093
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Node: Searching340137
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Node: Readline Init File342323
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Node: Readline Init File Syntax343584
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Node: Conditional Init Constructs365072
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Node: Sample Init File369268
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Node: Bindable Readline Commands372392
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Node: Commands For Moving373596
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Node: Commands For History375647
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Node: Commands For Text380641
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Node: Commands For Killing384290
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Node: Numeric Arguments387323
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Node: Commands For Completion388462
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Node: Keyboard Macros392653
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Node: Miscellaneous Commands393340
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Node: Readline vi Mode399279
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Node: Programmable Completion400186
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Node: Programmable Completion Builtins407966
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Node: A Programmable Completion Example418661
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Node: Using History Interactively423908
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Node: Bash History Facilities424592
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Node: Bash History Builtins427597
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Node: History Interaction432605
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Node: Event Designators436225
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Node: Word Designators437579
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Node: Modifiers439339
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Node: Installing Bash441150
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Node: Basic Installation442287
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Node: Compilers and Options446009
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Node: Compiling For Multiple Architectures446750
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Node: Installation Names448443
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Node: Specifying the System Type450552
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Node: Sharing Defaults451268
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Node: Operation Controls451941
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Node: Optional Features452899
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Node: Reporting Bugs464117
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Node: Major Differences From The Bourne Shell465392
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Node: GNU Free Documentation License482242
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Node: Indexes507419
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Node: Builtin Index507873
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Node: Reserved Word Index514700
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Node: Variable Index517148
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Node: Function Index533640
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Node: Concept Index547424
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Node: Shell Compatibility Mode310277
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Node: Job Control318306
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Node: Job Control Basics318766
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Node: Job Control Builtins323768
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Node: Job Control Variables329168
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Node: Command Line Editing330324
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Node: Introduction and Notation331995
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Node: Readline Interaction333618
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Node: Readline Bare Essentials334809
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Node: Readline Movement Commands336592
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Node: Readline Killing Commands337552
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Node: Readline Arguments339470
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Node: Searching340514
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Node: Readline Init File342700
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Node: Readline Init File Syntax343961
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Node: Conditional Init Constructs365449
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Node: Sample Init File369645
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||||
Node: Bindable Readline Commands372769
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Node: Commands For Moving373973
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||||
Node: Commands For History376024
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||||
Node: Commands For Text381018
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||||
Node: Commands For Killing384667
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||||
Node: Numeric Arguments387700
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||||
Node: Commands For Completion388839
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||||
Node: Keyboard Macros393030
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||||
Node: Miscellaneous Commands393717
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||||
Node: Readline vi Mode399656
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Node: Programmable Completion400563
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Node: Programmable Completion Builtins408343
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Node: A Programmable Completion Example419038
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Node: Using History Interactively424285
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||||
Node: Bash History Facilities424969
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||||
Node: Bash History Builtins427974
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Node: History Interaction432982
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Node: Event Designators436602
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Node: Word Designators437956
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||||
Node: Modifiers439716
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||||
Node: Installing Bash441527
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||||
Node: Basic Installation442664
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||||
Node: Compilers and Options446386
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||||
Node: Compiling For Multiple Architectures447127
|
||||
Node: Installation Names448820
|
||||
Node: Specifying the System Type450929
|
||||
Node: Sharing Defaults451645
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||||
Node: Operation Controls452318
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||||
Node: Optional Features453276
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||||
Node: Reporting Bugs464494
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Node: Major Differences From The Bourne Shell465769
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||||
Node: GNU Free Documentation License482619
|
||||
Node: Indexes507796
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Node: Builtin Index508250
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Node: Reserved Word Index515077
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Node: Variable Index517525
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Node: Function Index534017
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Node: Concept Index547801
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End Tag Table
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