dmbcs/i-bash
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Bash-4.2 distribution sources and documentation

Browse source
This commit is contained in:
Chet Ramey 2011-11-22 19:11:26 -05:00
commit 495aee441b
341 changed files with 108751 additions and 36060 deletions
Download patch file Download diff file Expand all files Collapse all files

87
POSIX
View file

@ -55,116 +55,129 @@ The following list is what's changed when `POSIX mode' is in effect:
13. Non-interactive shells exit if a syntax error in an arithmetic
expansion results in an invalid expression.
14. Redirection operators do not perform filename expansion on the word
14. Non-interactive shells exit if there is a syntax error in a script
read with the `.' or `source' builtins, or in a string processed by
the `eval' builtin.
15. Redirection operators do not perform filename expansion on the word
in the redirection unless the shell is interactive.
15. Redirection operators do not perform word splitting on the word in
16. Redirection operators do not perform word splitting on the word in
the redirection.
16. Function names must be valid shell `name's. That is, they may not
17. 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.
17. POSIX special builtins are found before shell functions during
18. POSIX special builtins are found before shell functions during
command lookup.
18. If a POSIX special builtin returns an error status, a
19. The `time' reserved word may be used by itself as a command. When
used in this way, it displays timing statistics for the shell and
its completed children. The `TIMEFORMAT' variable controls the
format of the timing information.
20. When parsing and expanding a ${...} expansion that appears within
double quotes, single quotes are no longer special and cannot be
used to quote a closing brace or other special character, unless
the operator is one of those defined to perform pattern removal.
In this case, they do not have to appear as matched pairs.
21. The parser does not recognize `time' as a reserved word if the next
token begins with a `-'.
22. If a POSIX special builtin returns an error status, a
non-interactive shell exits. The fatal errors are those listed in
the POSIX standard, and include things like passing incorrect
options, redirection errors, variable assignment errors for
assignments preceding the command name, and so on.
19. If `CDPATH' is set, the `cd' builtin will not implicitly append
the current directory to it. This means that `cd' will fail if no
valid directory name can be constructed from any of the entries in
`$CDPATH', even if the a directory with the same name as the name
given as an argument to `cd' exists in the current directory.
20. A non-interactive shell exits with an error status if a variable
23. A non-interactive shell exits with an error status if a variable
assignment error occurs when no command name follows the assignment
statements. A variable assignment error occurs, for example, when
trying to assign a value to a readonly variable.
21. A non-interactive shell exits with an error status if the iteration
24. A non-interactive shell exists with an error status if a variable
assignment error occurs in an assignment statement preceding a
special builtin, but not with any other simple command.
25. A non-interactive shell exits with an error status if the iteration
variable in a `for' statement or the selection variable in a
`select' statement is a readonly variable.
22. Process substitution is not available.
26. Process substitution is not available.
23. Assignment statements preceding POSIX special builtins persist in
27. Assignment statements preceding POSIX special builtins persist in
the shell environment after the builtin completes.
24. Assignment statements preceding shell function calls persist in the
28. 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.
25. The `export' and `readonly' builtin commands display their output
29. The `export' and `readonly' builtin commands display their output
in the format required by POSIX.
26. The `trap' builtin displays signal names without the leading `SIG'.
30. The `trap' builtin displays signal names without the leading `SIG'.
27. The `trap' builtin doesn't check the first argument for a possible
31. 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.
28. The `.' and `source' builtins do not search the current directory
32. The `.' and `source' builtins do not search the current directory
for the filename argument if it is not found by searching `PATH'.
29. Subshells spawned to execute command substitutions inherit the
33. Subshells spawned to execute command substitutions inherit the
value of the `-e' option from the parent shell. When not in POSIX
mode, Bash clears the `-e' option in such subshells.
30. Alias expansion is always enabled, even in non-interactive shells.
34. Alias expansion is always enabled, even in non-interactive shells.
31. When the `alias' builtin displays alias definitions, it does not
35. When the `alias' builtin displays alias definitions, it does not
display them with a leading `alias ' unless the `-p' option is
supplied.
32. When the `set' builtin is invoked without options, it does not
36. When the `set' builtin is invoked without options, it does not
display shell function names and definitions.
33. When the `set' builtin is invoked without options, it displays
37. 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.
34. When the `cd' builtin is invoked in LOGICAL mode, and the pathname
38. When the `cd' builtin is invoked in LOGICAL mode, and the pathname
constructed from `$PWD' and the directory name supplied as an
argument does not refer to an existing directory, `cd' will fail
instead of falling back to PHYSICAL mode.
35. When the `pwd' builtin is supplied the `-P' option, it resets
`$PWD' to a pathname containing no symlinks.
36. The `pwd' builtin verifies that the value it prints is the same as
39. 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
40. 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'.
41. The default editor used by `fc' is `ed'.
39. The `type' and `command' builtins will not report a non-executable
42. 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
`$PATH'.
40. The `vi' editing mode will invoke the `vi' editor directly when
43. The `vi' editing mode will invoke the `vi' editor directly when
the `v' command is run, instead of checking `$VISUAL' and
`$EDITOR'.
41. When the `xpg_echo' option is enabled, Bash does not attempt to
44. 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.
42. The `ulimit' builtin uses a block size of 512 bytes for the `-c'
45. The `ulimit' builtin uses a block size of 512 bytes for the `-c'
and `-f' options.
43. The arrival of `SIGCHLD' when a trap is set on `SIGCHLD' does not
46. 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.