выполнить расширение слова как posix-оболочку (perform word expansion like a posix-shell)
Имя (Name)
wordexp, wordfree - perform word expansion like a posix-shell
Синопсис (Synopsis)
#include <wordexp.h>
int wordexp(const char *restrict s, wordexp_t *restrict p, int flags);
void wordfree(wordexp_t *p);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
wordexp(), wordfree():
_XOPEN_SOURCE
Описание (Description)
The function wordexp() performs a shell-like expansion of the
string s and returns the result in the structure pointed to by p.
The data type wordexp_t is a structure that at least has the
fields we_wordc, we_wordv, and we_offs. The field we_wordc is a
size_t that gives the number of words in the expansion of s. The
field we_wordv is a char ** that points to the array of words
found. The field we_offs of type size_t is sometimes (depending
on flags, see below) used to indicate the number of initial
elements in the we_wordv array that should be filled with NULLs.
The function wordfree() frees the allocated memory again. More
precisely, it does not free its argument, but it frees the array
we_wordv and the strings that points to.
The string argument
Since the expansion is the same as the expansion by the shell
(see sh(1)) of the parameters to a command, the string s must not
contain characters that would be illegal in shell command
parameters. In particular, there must not be any unescaped
newline or |, &, ;, <, >, (, ), {, } characters outside a command
substitution or parameter substitution context.
If the argument s contains a word that starts with an unquoted
comment character #, then it is unspecified whether that word and
all following words are ignored, or the # is treated as a non-
comment character.
The expansion
The expansion done consists of the following stages: tilde
expansion (replacing ~user by user's home directory), variable
substitution (replacing $FOO by the value of the environment
variable FOO), command substitution (replacing $(command) or
`command` by the output of command), arithmetic expansion, field
splitting, wildcard expansion, quote removal.
The result of expansion of special parameters ($@, $*, $#, $?,
$-, $$, $!, $0) is unspecified.
Field splitting is done using the environment variable $IFS. If
it is not set, the field separators are space, tab, and newline.
The output array
The array we_wordv contains the words found, followed by a NULL.
The flags argument
The flag argument is a bitwise inclusive OR of the following
values:
WRDE_APPEND
Append the words found to the array resulting from a
previous call.
WRDE_DOOFFS
Insert we_offs initial NULLs in the array we_wordv.
(These are not counted in the returned we_wordc.)
WRDE_NOCMD
Don't do command substitution.
WRDE_REUSE
The argument p resulted from a previous call to wordexp(),
and wordfree() was not called. Reuse the allocated
storage.
WRDE_SHOWERR
Normally during command substitution stderr is redirected
to /dev/null. This flag specifies that stderr is not to
be redirected.
WRDE_UNDEF
Consider it an error if an undefined shell variable is
expanded.
Возвращаемое значение (Return value)
On success, wordexp() returns 0. On failure, wordexp() returns
one of the following nonzero values:
WRDE_BADCHAR
Illegal occurrence of newline or one of |, &, ;, <, >, (,
), {, }.
WRDE_BADVAL
An undefined shell variable was referenced, and the
WRDE_UNDEF flag told us to consider this an error.
WRDE_CMDSUB
Command substitution requested, but the WRDE_NOCMD flag
told us to consider this an error.
WRDE_NOSPACE
Out of memory.
WRDE_SYNTAX
Shell syntax error, such as unbalanced parentheses or
unmatched quotes.
Версии (Versions)
wordexp() and wordfree() are provided in glibc since version 2.1.
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
attributes(7).
┌───────────┬───────────────┬────────────────────────────────────┐
│Interface │ Attribute │ Value │
├───────────┼───────────────┼────────────────────────────────────┤
│wordexp() │ Thread safety │ MT-Unsafe race:utent const:env env │
│ │ │ sig:ALRM timer locale │
├───────────┼───────────────┼────────────────────────────────────┤
│wordfree() │ Thread safety │ MT-Safe │
└───────────┴───────────────┴────────────────────────────────────┘
In the above table, utent in race:utent signifies that if any of
the functions setutent(3), getutent(3), or endutent(3) are used
in parallel in different threads of a program, then data races
could occur. wordexp() calls those functions, so we use
race:utent to remind users.
Стандарты (Conforming to)
POSIX.1-2001, POSIX.1-2008.
Примеры (Examples)
The output of the following example program is approximately that
of "ls [a-c]*.c".
#include <stdio.h>
#include <stdlib.h>
#include <wordexp.h>
int
main(int argc, char *argv[])
{
wordexp_t p;
char **w;
wordexp("[a-c]*.c", &p, 0);
w = p.we_wordv;
for (int i = 0; i < p.we_wordc; i++)
printf("%s\n", w[i]);
wordfree(&p);
exit(EXIT_SUCCESS);
}
Смотри также (See also)
fnmatch(3), glob(3)
