Standard C Library Functions wordexp(3C)
NAME
wordexp, wordfree - perform word expansions
SYNOPSIS
#include
int wordexp(const char *restrict words, wordexp_t *restrict pwordexp,
int flags);void wordfree(wordexp_t *pwordexp);
DESCRIPTION
The wordexp() function performs word expansions, subject to quoting, and places the list of expanded words into the structure pointed to by pwordexp.The wordfree() function frees any memory allocated by wor-
dexp() associated with pwordexp. words Argument The words argument is a pointer to a string containing one or more words to be expanded. The expansions will be the same as would be performed by the shell if words were thepart of a command line representing the arguments to a util-
ity. Therefore, words must not contain an unquoted NEWLINE or any of the unquoted shell special characters: | & ; < > except in the context of command substitution. It also must not contain unquoted parentheses or braces, except in the context of command or variable substitution. If the argument words contains an unquoted comment character (number sign) that is the beginning of a token, wordexp() may treat the comment character as a regular character, or may interpret it as a comment indicator and ignore the remainder of words. pwordexp ArgumentThe structure type wordexp_t is defined in the header
and includes at least the following members: size_t we_wordc Count of words matched by words.
char **we_wordv Pointer to list of expanded words.
SunOS 5.11 Last change: 1 Nov 2003 1
Standard C Library Functions wordexp(3C)size_t we_offs Slots to reserve at the beginning of
pwordexp->we_wordv.
The wordexp() function stores the number of generated wordsinto pwordexp->we_wordc and a pointer to a list of pointers
to words in pwordexp->we_wordv. Each individual field
created during field splitting is a separate word in thepwordexp->we_wordv list. The words are in order. The first
pointer after the last word pointer will be a null pointer. It is the caller's responsibility to allocate the storage pointed to by pwordexp. The wordexp() function allocates other space as needed, including memory pointed to bypwordexp->we_wordv. The wordfree() function frees any memory
associated with pwordexp from a previous call to wordexp(). flags ArgumentThe flags argument is used to control the behavior of wor-
dexp(). The value of flags is the bitwise inclusive OR of zero or more of the following constants, which are defined in: WRDE_APPEND Append words generated to the ones from a
previous call to wordexp().WRDE_DOOFFS Make use of pwordexp->we_offs. If this flag
is set, pwordexp->we_offs is used to specify
how many NULL pointers to add to the begin-
ning of pwordexp->we_wordv. In other words,
pwordexp->we_wordv will point to
pwordexp->we_offs NULL pointers, followed by
pwordexp->we_wordc word pointers, followed
by a NULL pointer.WRDE_NOCMD Fail if command substitution is requested.
WRDE_REUSE The pwordexp argument was passed to a previ-
ous successful call to wordexp(), and hasnot been passed to wordfree(). The result
will be the same as if the application hadcalled wordfree() and then called wordexp()
without WRDE_REUSE.
WRDE_SHOWERR Do not redirect stderr to /dev/null.
SunOS 5.11 Last change: 1 Nov 2003 2
Standard C Library Functions wordexp(3C)WRDE_UNDEF Report error on an attempt to expand an
undefined shell variable.The WRDE_APPEND flag can be used to append a new set of
words to those generated by a previous call to wordexp().The following rules apply when two or more calls to wor-
dexp() are made with the same value of pwordexp and withoutintervening calls to wordfree():
1. The first such call must not set WRDE_APPEND. All
subsequent calls must set it.2. All of the calls must set WRDE_DOOFFS, or all must
not set it. 3. After the second and each subsequent call,pwordexp->we_wordv will point to a list containing
the following: a. zero or more NULL pointers, as specified byWRDE_DOOFFS and pwordexp->we_offs.
b. pointers to the words that were in thepwordexp->we_wordv list before the call, in the
same order as before. c. pointers to the new words generated by the latest call, in the specified order.4. The count returned in pwordexp->we_wordc will be
the total number of words from all of the calls. 5. The application can change any of the fields after a call to wordexp(), but if it does it must reset them to the original value before a subsequentcall, using the same pwordexp value, to wordfree()
or wordexp() with the WRDE_APPEND or WRDE_REUSE
flag. If words contains an unquoted: NEWLINE | & ; < > ( ) { } in an inappropriate context, wordexp() will fail, and the number of expanded words will be zero.SunOS 5.11 Last change: 1 Nov 2003 3
Standard C Library Functions wordexp(3C)Unless WRDE_SHOWERR is set in flags, wordexp() will redirect
stderr to /dev/null for any utilities executed as a result of command substitution while expanding words.If WRDE_SHOWERR is set, wordexp() may write messages to
stderr if syntax errors are detected while expanding words.If WRDE_DOOFFS is set, then pwordexp-> we_offs must have the
same value for each wordexp() call and wordfree() call using
a given pwordexp. The following constants are defined as error return values:WRDE_BADCHAR One of the unquoted characters:
NEWLINE | & ; < > ( ) { }appears in words in an inappropriate con-
text.WRDE_BADVAL Reference to undefined shell variable when
WRDE_UNDEF is set in flags.
WRDE_CMDSUB Command substitution requested when
WRDE_NOCMD was set in flags.
WRDE_NOSPACE Attempt to allocate memory failed.
WRDE_SYNTAX Shell syntax error, such as unbalanced
parentheses or unterminated string.RETURN VALUES
On successful completion, wordexp() returns 0.Otherwise, a non-zero value as described in
returned to indicate an error. If wordexp() returns theis value WRDE_NOSPACE, then pwordexp->we_wordc and
pwordexp->we_wordv will be updated to reflect any words that
were successfully expanded. In other cases, they will not be modified.The wordfree() function returns no value.
SunOS 5.11 Last change: 1 Nov 2003 4
Standard C Library Functions wordexp(3C)ERRORS
No errors are defined.USAGE
This function is intended to be used by an application that wants to do all of the shell's expansions on a word or words obtained from a user. For example, if the application prompts for a filename (or list of filenames) and then uses wordexp() to process the input, the user could respond with anything that would be valid as input to the shell.The WRDE_NOCMD flag is provided for applications that, for
security or other reasons, want to prevent a user from exe-
cuting shell command. Disallowing unquoted shell specialcharacters also prevents unwanted side effects such as exe-
cuting a command or writing a file.ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| MT-Level | MT-Safe |
|_____________________________|_____________________________|
| Standard | See standards(5). ||_____________________________|_____________________________|
SEE ALSO
fnmatch(3C), glob(3C), attributes(5), standards(5)SunOS 5.11 Last change: 1 Nov 2003 5