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| Next: <a rel="next" accesskey="n" href="Flags-for-Wordexp.html#Flags-for-Wordexp">Flags for Wordexp</a>, |
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| <h4 class="subsection">10.4.2 Calling <code>wordexp</code></h4> |
| |
| <p>All the functions, constants and data types for word expansion are |
| declared in the header file <samp><span class="file">wordexp.h</span></samp>. |
| |
| <p>Word expansion produces a vector of words (strings). To return this |
| vector, <code>wordexp</code> uses a special data type, <code>wordexp_t</code>, which |
| is a structure. You pass <code>wordexp</code> the address of the structure, |
| and it fills in the structure's fields to tell you about the results. |
| |
| <!-- wordexp.h --> |
| <!-- POSIX.2 --> |
| <div class="defun"> |
| — Data Type: <b>wordexp_t</b><var><a name="index-wordexp_005ft-895"></a></var><br> |
| <blockquote><p>This data type holds a pointer to a word vector. More precisely, it |
| records both the address of the word vector and its size. |
| |
| <dl> |
| <dt><code>we_wordc</code><dd>The number of elements in the vector. |
| |
| <br><dt><code>we_wordv</code><dd>The address of the vector. This field has type <code>char **</code><!-- /@w -->. |
| |
| <br><dt><code>we_offs</code><dd>The offset of the first real element of the vector, from its nominal |
| address in the <code>we_wordv</code> field. Unlike the other fields, this |
| is always an input to <code>wordexp</code>, rather than an output from it. |
| |
| <p>If you use a nonzero offset, then that many elements at the beginning of |
| the vector are left empty. (The <code>wordexp</code> function fills them with |
| null pointers.) |
| |
| <p>The <code>we_offs</code> field is meaningful only if you use the |
| <code>WRDE_DOOFFS</code> flag. Otherwise, the offset is always zero |
| regardless of what is in this field, and the first real element comes at |
| the beginning of the vector. |
| </dl> |
| </p></blockquote></div> |
| |
| <!-- wordexp.h --> |
| <!-- POSIX.2 --> |
| <div class="defun"> |
| — Function: int <b>wordexp</b> (<var>const char *words, wordexp_t *word-vector-ptr, int flags</var>)<var><a name="index-wordexp-896"></a></var><br> |
| <blockquote><p>Perform word expansion on the string <var>words</var>, putting the result in |
| a newly allocated vector, and store the size and address of this vector |
| into <code>*</code><var>word-vector-ptr</var>. The argument <var>flags</var> is a |
| combination of bit flags; see <a href="Flags-for-Wordexp.html#Flags-for-Wordexp">Flags for Wordexp</a>, for details of |
| the flags. |
| |
| <p>You shouldn't use any of the characters ‘<samp><span class="samp">|&;<></span></samp>’ in the string |
| <var>words</var> unless they are quoted; likewise for newline. If you use |
| these characters unquoted, you will get the <code>WRDE_BADCHAR</code> error |
| code. Don't use parentheses or braces unless they are quoted or part of |
| a word expansion construct. If you use quotation characters ‘<samp><span class="samp">'"`</span></samp>’, |
| they should come in pairs that balance. |
| |
| <p>The results of word expansion are a sequence of words. The function |
| <code>wordexp</code> allocates a string for each resulting word, then |
| allocates a vector of type <code>char **</code> to store the addresses of |
| these strings. The last element of the vector is a null pointer. |
| This vector is called the <dfn>word vector</dfn>. |
| |
| <p>To return this vector, <code>wordexp</code> stores both its address and its |
| length (number of elements, not counting the terminating null pointer) |
| into <code>*</code><var>word-vector-ptr</var>. |
| |
| <p>If <code>wordexp</code> succeeds, it returns 0. Otherwise, it returns one |
| of these error codes: |
| |
| <dl> |
| <!-- wordexp.h --> |
| <!-- POSIX.2 --> |
| <dt><code>WRDE_BADCHAR</code><dd>The input string <var>words</var> contains an unquoted invalid character such |
| as ‘<samp><span class="samp">|</span></samp>’. |
| |
| <!-- wordexp.h --> |
| <!-- POSIX.2 --> |
| <br><dt><code>WRDE_BADVAL</code><dd>The input string refers to an undefined shell variable, and you used the flag |
| <code>WRDE_UNDEF</code> to forbid such references. |
| |
| <!-- wordexp.h --> |
| <!-- POSIX.2 --> |
| <br><dt><code>WRDE_CMDSUB</code><dd>The input string uses command substitution, and you used the flag |
| <code>WRDE_NOCMD</code> to forbid command substitution. |
| |
| <!-- wordexp.h --> |
| <!-- POSIX.2 --> |
| <br><dt><code>WRDE_NOSPACE</code><dd>It was impossible to allocate memory to hold the result. In this case, |
| <code>wordexp</code> can store part of the results—as much as it could |
| allocate room for. |
| |
| <!-- wordexp.h --> |
| <!-- POSIX.2 --> |
| <br><dt><code>WRDE_SYNTAX</code><dd>There was a syntax error in the input string. For example, an unmatched |
| quoting character is a syntax error. |
| </dl> |
| </p></blockquote></div> |
| |
| <!-- wordexp.h --> |
| <!-- POSIX.2 --> |
| <div class="defun"> |
| — Function: void <b>wordfree</b> (<var>wordexp_t *word-vector-ptr</var>)<var><a name="index-wordfree-897"></a></var><br> |
| <blockquote><p>Free the storage used for the word-strings and vector that |
| <code>*</code><var>word-vector-ptr</var> points to. This does not free the |
| structure <code>*</code><var>word-vector-ptr</var> itself—only the other |
| data it points to. |
| </p></blockquote></div> |
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