WORDEXP(3) BSD Library Functions Manual WORDEXP(3)NAMEwordexp — perform shell-style word expansions
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <wordexp.h>
int
wordexp(const char * restrict words, wordexp_t * restrict we, int flags);
void
wordfree(wordexp_t *we);
DESCRIPTION
The wordexp() function performs shell-style word expansion on words and
places the list of words into the we_wordv member of we, and the number
of words into we_wordc.
The flags argument is the bitwise inclusive OR of any of the following
constants:
WRDE_APPEND Append the words to those generated by a previous call to
wordexp().
WRDE_DOOFFS As many NULL pointers as are specified by the we_offs mem‐
ber of we are added to the front of we_wordv.
WRDE_NOCMD Disallow command substitution in words. See the note in
BUGS before using this.
WRDE_REUSE The we argument was passed to a previous successful call to
wordexp() but has not been passed to wordfree(). The
implementation may reuse the space allocated to it.
WRDE_SHOWERR Do not redirect shell error messages to /dev/null.
WRDE_UNDEF Report error on an attempt to expand an undefined shell
variable.
The wordexp_t structure is defined in <wordexp.h> as:
typedef struct {
size_t we_wordc; /* count of words matched */
char **we_wordv; /* pointer to list of words */
size_t we_offs; /* slots to reserve in we_wordv */
} wordexp_t;
The wordfree() function frees the memory allocated by wordexp().
IMPLEMENTATION NOTES
The wordexp() function is implemented as a wrapper around the undocu‐
mented wordexp shell built-in command.
RETURN VALUES
The wordexp() function returns zero if successful, otherwise it returns
one of the following error codes:
WRDE_BADCHAR The words argument contains one of the following unquoted
characters: ⟨newline⟩, ‘|’, ‘&’, ‘;’, ‘<’, ‘>’, ‘(’, ‘)’,
‘{’, ‘}’.
WRDE_BADVAL An attempt was made to expand an undefined shell variable
and WRDE_UNDEF is set in flags.
WRDE_CMDSUB An attempt was made to use command substitution and
WRDE_NOCMD is set in flags.
WRDE_NOSPACE Not enough memory to store the result.
WRDE_SYNTAX Shell syntax error in words.
The wordfree() function returns no value.
ENVIRONMENT
IFS Field separator.
EXAMPLES
Invoke the editor on all .c files in the current directory and /etc/motd
(error checking omitted):
wordexp_t we;
wordexp("${EDITOR:-vi} *.c /etc/motd", &we, 0);
execvp(we.we_wordv[0], we.we_wordv);
DIAGNOSTICS
Diagnostic messages from the shell are written to the standard error out‐
put if WRDE_SHOWERR is set in flags.
SEE ALSOsh(1), fnmatch(3), glob(3), popen(3), system(3)STANDARDS
The wordexp() and wordfree() functions conform to IEEE Std 1003.1-2001
(“POSIX.1”).
BUGS
Do not pass untrusted user data to wordexp(), regardless of whether the
WRDE_NOCMD flag is set. The wordexp() function attempts to detect input
that would cause commands to be executed before passing it to the shell
but it does not use the same parser so it may be fooled.
The current wordexp() implementation does not recognize multibyte charac‐
ters, since the shell (which it invokes to perform expansions) does not.
BSD July 29, 2004 BSD
