wordexp(3) - Linux manual page (original) (raw)
wordexp(3) Library Functions Manual wordexp(3)
NAME top
wordexp, wordfree - perform word expansion like a posix-shellLIBRARY top
Standard C library (_libc_, _-lc_)SYNOPSIS top
**#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_SOURCEDESCRIPTION top
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 _wordexpt_ is a structure that at least has the
fields _wewordc_, _wewordv_, and _weoffs_. The field _wewordc_ is a
_sizet_ that gives the number of words in the expansion of _s_. The
field _wewordv_ is a _char **_ that points to the array of words
found. The field _weoffs_ of type _sizet_ is sometimes (depending
on _flags_, see below) used to indicate the number of initial
elements in the _wewordv_ 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
_wewordv_ 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 $(command) or
command by the output of command), arithmetic expansion, field
splitting, wildcard expansion, quote removal.
The result of expansion of special parameters ($@, <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mo>∗</mo><mo separator="true">,</mo></mrow><annotation encoding="application/x-tex">*, </annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6597em;vertical-align:-0.1944em;"></span><span class="mord">∗</span><span class="mpunct">,</span></span></span></span>#, <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mo stretchy="false">?</mo><mo separator="true">,</mo></mrow><annotation encoding="application/x-tex">?, </annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mclose">?</span><span class="mpunct">,</span></span></span></span>-,
<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow></mrow><annotation encoding="application/x-tex"></annotation></semantics></math></span><span class="katex-html" aria-hidden="true"></span></span>, <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mo stretchy="false">!</mo><mo separator="true">,</mo></mrow><annotation encoding="application/x-tex">!, </annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mclose">!</span><span class="mpunct">,</span></span></span></span>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 wewordv 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 _weoffs_ initial NULLs in the array _wewordv_. (These
are not counted in the returned _wewordc_.)
**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.RETURN VALUE top
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.ATTRIBUTES top
For an explanation of the terms used in this section, see
[attributes(7)](../man7/attributes.7.html).
┌────────────┬───────────────┬───────────────────────────────────┐
│ **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)](../man3/setutent.3.html), [getutent(3)](../man3/getutent.3.html), or [endutent(3)](../man3/endutent.3.html) 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.STANDARDS top
POSIX.1-2008.HISTORY top
POSIX.1-2001. glibc 2.1.EXAMPLES top
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(void)
{
wordexp_t p;
char **w;
wordexp("[a-c]*.c", &p, 0);
w = p.we_wordv;
for (size_t i = 0; i < p.we_wordc; i++)
printf("%s\n", w[i]);
wordfree(&p);
exit(EXIT_SUCCESS);
}SEE ALSO top
[fnmatch(3)](../man3/fnmatch.3.html), [glob(3)](../man3/glob.3.html)COLOPHON top
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man-pages@man7.orgLinux man-pages 6.10 2024-07-23 wordexp(3)
Pages that refer to this page:fnmatch(3), glob(3)