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Under GNU General Public License
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WORDEXP(3) Linux Programmer's Manual WORDEXP(3)
NAME
wordexp, wordfree - perform word expansion like a posix-shell
SYNOPSIS
#include <wordexp.h>
int wordexp(const char *s, wordexp_t *p, int flags);
void wordfree(wordexp_t *p);
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 struc-
ture 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 indi-
cate 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.
EXAMPLE
First a small example. The output is approximately that of "ls [a-c]*.c".
#include <stdio.h>
#include <wordexp.h>
int main(int argc, char **argv) {
wordexp_t p;
char **w;
int i;
wordexp("[a-c]*.c", &p, 0);
w = p.we_wordv;
for (i=0; i<p.we_wordc; i++)
printf("%s\n", w[i]);
wordfree(&p);
return 0;
}
DETAILS
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 non-
escaped newline or |, &, ;, <, >, (, ), {, } characters outside a command substitu-
tion 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 $(command) or
'command' by the output of command), arithmetic expansion, field splitting, wild-
card expansion, quote removal.
The result of expansion of special parameters ($@, $*, $#, $?, $-, $$, $!, $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 parameter 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
In case of success 0 is returned. In case of error one of the following five values
is returned.
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 occurred, and 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.
CONFORMING TO
POSIX.1-2001
SEE ALSO
fnmatch(3), glob(3)
2003-11-11 WORDEXP(3)
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On Apache/1.3.37 (Unix) mod_throttle/3.1.2 FrontPage/5.0.2.2635 mod_psoft_traffic/0.2 mod_ssl/2.8.28 OpenSSL/0.9.8b
Under GNU General Public License
2009-01-07 20:39 @38.103.63.55 Crawled by CCBot/1.0 (+http://www.commoncrawl.org/bot.html)