--- /dev/null
+Brace Expansion
+
+Brace expansion is a mechanism by which arbitrary strings may be gener-
+ated. This mechanism is similar to pathname expansion, but the file-
+names generated need not exist. Patterns to be brace expanded take the
+form of an optional preamble, followed by either a series of comma-sep-
+arated strings or a sequence expression between a pair of braces, fol-
+lowed by an optional postscript. The preamble is prefixed to each
+string contained within the braces, and the postscript is then appended
+to each resulting string, expanding left to right.
+
+Brace expansions may be nested. The results of each expanded string
+are not sorted; left to right order is preserved. For example,
+a{d,c,b}e expands into `ade ace abe'.
+
+A sequence expression takes the form {x..y}, where x and y are either
+integers or single characters. When integers are supplied, the expres-
+sion expands to each number between x and y, inclusive. When charac-
+ters are supplied, the expression expands to each character lexico-
+graphically between x and y, inclusive. Note that both x and y must be
+of the same type.
+
+Brace expansion is performed before any other expansions, and any char-
+acters special to other expansions are preserved in the result. It is
+strictly textual. Bash does not apply any syntactic interpretation to
+the context of the expansion or the text between the braces.
+
+A correctly-formed brace expansion must contain unquoted opening and
+closing braces, and at least one unquoted comma or a valid sequence
+expression. Any incorrectly formed brace expansion is left unchanged.
+A { or , may be quoted with a backslash to prevent its being considered
+part of a brace expression. To avoid conflicts with parameter expan-
+sion, the string ${ is not considered eligible for brace expansion.
+
+This construct is typically used as shorthand when the common prefix of
+the strings to be generated is longer than in the above example:
+
+ mkdir /usr/local/src/bash/{old,new,dist,bugs}
+or
+ chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}}
+
+Brace expansion introduces a slight incompatibility with historical
+versions of sh. sh does not treat opening or closing braces specially
+when they appear as part of a word, and preserves them in the output.
+Bash removes braces from words as a consequence of brace expansion.
+For example, a word entered to sh as file{1,2} appears identically in
+the output. The same word is output as file1 file2 after expansion by
+bash. If strict compatibility with sh is desired, start bash with the
++B option or disable brace expansion with the +B option to the set com-
+mand
* expanded result may need to be globbed
* and $IFS-splitted */
debug_printf_subst("SUBST '%s' first_ch %x\n", arg, first_ch);
- process_command_subs(&subst_result, arg);
+ G.last_exitcode = process_command_subs(&subst_result, arg);
debug_printf_subst("SUBST RES '%s'\n", subst_result.data);
val = subst_result.data;
goto store_val;
/* if someone gives us an empty string: `cmd with empty output` */
if (!argv_expanded[0]) {
debug_leave();
- return 0;
+ return 0; // or G.last_exitcode? see emptytick.tests
}
x = find_builtin(argv_expanded[0]);
#if ENABLE_HUSH_TICK
-static FILE *generate_stream_from_string(const char *s)
+static FILE *generate_stream_from_string(const char *s, pid_t *pid_p)
{
- FILE *pf;
- int pid, channel[2];
+ pid_t pid;
+ int channel[2];
# if !BB_MMU
char **to_free;
# endif
}
/* parent */
+ *pid_p = pid;
# if ENABLE_HUSH_FAST
G.count_SIGCHLD++;
//bb_error_msg("[%d] fork in generate_stream_from_string: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
free(to_free);
# endif
close(channel[1]);
- pf = fdopen(channel[0], "r");
- return pf;
+//TODO: libbb: fdopen_or_die?
+ return fdopen(channel[0], "r");
}
/* Return code is exit status of the process that is run. */
{
FILE *pf;
struct in_str pipe_str;
- int ch, eol_cnt;
+ pid_t pid;
+ int status, ch, eol_cnt;
- pf = generate_stream_from_string(s);
+ pf = generate_stream_from_string(s, &pid);
if (pf == NULL)
return 1;
close_on_exec_on(fileno(pf));
o_addQchr(dest, ch);
}
- debug_printf("done reading from pipe, pclose()ing\n");
- /* Note: we got EOF, and we just close the read end of the pipe.
- * We do not wait for the `cmd` child to terminate. bash and ash do.
- * Try these:
- * echo `echo Hi; exec 1>&-; sleep 2` - bash waits 2 sec
- * `false`; echo $? - bash outputs "1"
- */
+ debug_printf("done reading from `cmd` pipe, closing it\n");
fclose(pf);
- debug_printf("closed FILE from child. return 0\n");
- return 0;
+ /* We need to extract exitcode. Test case
+ * "true; echo `sleep 1; false` $?"
+ * should print 1 */
+ safe_waitpid(pid, &status, 0);
+ debug_printf("child exited. returning its exitcode:%d\n", WEXITSTATUS(status));
+ return WEXITSTATUS(status);
}
#endif /* ENABLE_HUSH_TICK */
projects / oweals / busybox.git / commitdiff