64 lines
2.4 KiB
Text
64 lines
2.4 KiB
Text
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Starting bash with the `-posix' command-line option or setting the variable
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POSIXLY_CORRECT while bash is running will cause bash to conform more
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closely to the Posix.2 standard by changing the behavior to match that
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specified by Posix.2 in areas where the bash default differs.
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The following list is what's changed when `posixly_correct' is enabled:
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1. When a command in the hash table no longer exists, bash will re-search
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$PATH to find the new location.
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2. The >& redirection does not redirect stdout and stderr.
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3. The message printed by the job control code and builtins when a job
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exits with a non-zero status is `Done(status)'.
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4. The <> redirection does not open a file for both stdin and stdout, but
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rather opens it for read-write on fd 0.
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5. Reserved words may not be aliased.
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6. The Posix.2 PS1 and PS2 expansions of `!' -> history number and `!!' -> `!'
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are enabled.
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7. Interactive comments are enabled by default. (Note that this version has
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them on by default anyway.)
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8. The Posix.2 startup files are executed ($ENV) rather than the normal bash
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files.
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9. Tilde expansion is only performed on assignments preceding a command name,
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rather than on all assignment statements on the line.
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10. The default history file is ~/.sh_history (default value of $HISTFILE).
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11. The output of `kill -l' prints all the signal names on a single line,
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separated by spaces.
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12. Non-interactive shells exit if `file' in `. file' is not found.
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13. Redirection operators do not perform pathname expansion on the word
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in the redirection unless the shell is interactive
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14. Function names must be valid shell identifiers. 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
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There is other Posix.2 behavior that bash does not implement. Specifically:
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1. There are no `special builtins' and `regular builtins'. All builtins
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are equivalent. This means that:
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o assignment statements affect the execution environment of all
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builtins, not just special ones
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o temporary assignments do not persist after Posix.2 special
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builtins complete
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o Functions are found before Posix.2 special builtins
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o The shell does not exit upon errors while executing Posix.2
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special builtins
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2. $LINENO does not represent the line number of a command within a function
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3. The arithmetic evaluator does not implement the `e ? e1 : e2' conditional
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expression
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