diff options
Diffstat (limited to 'POSIX')
| -rw-r--r-- | POSIX | 87 |
1 files changed, 50 insertions, 37 deletions
@@ -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. |