NAME
wordexp, wordfree - perform word expansion like a posix-shell SYNOPSIS
#include
int wordexp(const char *s, wordexpt *p, int flags); void wordfree(wordexpt *p); Feature Test Macro Requirements for glibc (see featuretestmacros(7)): wordexp(), wordfree(): XOPENSOURCE 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 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 pre‐ cisely, 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 par‐ ticular, there must not be any unescaped newline or |, &, ;, <, >, (, ), {, } characters outside a command substitution or parameter substi‐ tution 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 $(command) or `command` by the output of com‐ mand), arithmetic expansion, field splitting, wildcard expansion, quote removal.
The result of expansion of special parameters ($@, $*, $#, $?, $-, $$,
$!, $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 wewordv contains the words found, followed by a NULL. The flags argument The flag argument is a bitwise inclusive OR of the following values: WRDEAPPEND Append the words found to the array resulting from a previous call. WRDEDOOFFS Insert weoffs initial NULLs in the array wewordv. (These are not counted in the returned wewordc.) WRDENOCMD Don't do command substitution. WRDEREUSE The argument p resulted from a previous call to wordexp(), and wordfree() was not called. Reuse the allocated storage. WRDESHOWERR Normally during command substitution stderr is redirected to /dev/null. This flag specifies that stderr is not to be redi‐ rected. WRDEUNDEF 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 follow‐ ing five values is returned. WRDEBADCHAR Illegal occurrence of newline or one of |, &, ;, <, >, (, ), {, }. WRDEBADVAL An undefined shell variable was referenced, and the WRDEUNDEF flag told us to consider this an error. WRDECMDSUB Command substitution occurred, and the WRDENOCMD flag told us to consider this an error. WRDENOSPACE Out of memory. WRDESYNTAX Shell syntax error, such as unbalanced parentheses or unmatched quotes. VERSIONS wordexp() and wordfree() are provided in glibc since version 2.1. CONFORMING TO
POSIX.1-2001. EXAMPLE The output of the following example program is approximately that of
"ls [a-c]*.c".
#include
#include
#include
int main(int argc, char **argv) { wordexpt p; char **w; int i; wordexp("[a-c]*.c", &p, 0); w = p.wewordv; for (i = 0; i < p.wewordc; i++)
printf("%s\n", w[i]); wordfree(&p); exit(EXITSUCCESS); } SEE ALSO fnmatch(3), glob(3) COLOPHON
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2008-07-14 WORDEXP(3)