The
glob() function is a pathname generator that implements the rules for file name pattern matching used by the shell.
The include file
glob.h defines the structure type
glob_t, which contains at least the following fields:
typedef struct {
size_t gl_pathc; /* count of total paths so far */
size_t gl_matchc; /* count of paths matching pattern */
size_t gl_offs; /* reserved at beginning of gl_pathv */
int gl_flags; /* returned flags */
char **gl_pathv; /* list of paths matching pattern */
} glob_t;
The argument
pattern is a pointer to a pathname pattern to be expanded. The
glob() argument matches all accessible pathnames against the pattern and creates a list of the pathnames that match. In order to have access to a pathname,
glob() requires search permission on every component of a path except the last and read permission on each directory of any filename component of
pattern that contains any of the special characters ‘*', ‘?' or ‘['.
The
glob() argument stores the number of matched pathnames into the
gl_pathc field, and a pointer to a list of pointers to pathnames into the
gl_pathv field. The first pointer after the last pathname is
NULL. If the pattern does not match any pathnames, the returned number of matched paths is set to zero.
It is the caller's responsibility to create the structure pointed to by
pglob. The
glob() function allocates other space as needed, including the memory pointed to by
gl_pathv.
The argument
flags is used to modify the behavior of
glob(). The value of
flags is the bitwise inclusive OR of any of the following values defined in
glob.h:
GLOB_APPEND
Append pathnames generated to the ones from a previous call (or calls) to glob(). The value of gl_pathc will be the total matches found by this call and the previous call(s). The pathnames are appended to, not merged with the pathnames returned by the previous call(s). Between calls, the caller must not change the setting of the GLOB_DOOFFS flag, nor change the value of gl_offs when GLOB_DOOFFS is set, nor (obviously) call globfree() for pglob.
GLOB_DOOFFS
Make use of the gl_offs field. If this flag is set, gl_offs is used to specify how many NULL pointers to prepend to the beginning of the gl_pathv field. In other words, gl_pathv will point to gl_offs NULL pointers, followed by gl_pathc pathname pointers, followed by a NULL pointer.
GLOB_ERR
Causes glob() to return when it encounters a directory that it cannot open or read. Ordinarily, glob() continues to find matches.
GLOB_MARK
Each pathname that is a directory that matches pattern has a slash appended.
GLOB_NOCHECK
If pattern does not match any pathname, then glob() returns a list consisting of only pattern, with the number of total pathnames set to 1, and the number of matched pathnames set to 0.
GLOB_NOSORT
By default, the pathnames are sorted in ascending ASCII order; this flag prevents that sorting (speeding up glob()).
The following values may also be included in
flags, however, they are non-standard extensions to IEEE Std 1003.2 (“POSIX.2”).
GLOB_ALTDIRFUNC
The following additional fields in the pglob structure have been initialized with alternate functions for glob to use to open, read, and close directories and to get stat information on names found in those directories.
void *(*gl_opendir)(const char * name);
struct dirent *(*gl_readdir)(void *);
void (*gl_closedir)(void *);
int (*gl_lstat)(const char *name, struct stat *st);
int (*gl_stat)(const char *name, struct stat *st);
This extension is provided to allow programs such as
restore(8) to provide globbing from directories stored on tape.
GLOB_BRACE
Pre-process the pattern string to expand ‘{pat,pat,...}' strings like
csh(1). The pattern ‘{}' is left unexpanded for historical reasons (
csh(1) does the same thing to ease typing of
find(1) patterns).
GLOB_MAGCHAR
Set by the glob() function if the pattern included globbing characters. See the description of the usage of the gl_matchc structure member for more details.
GLOB_NOMAGIC
Is the same as
GLOB_NOCHECK but it only appends the
pattern if it does not contain any of the special characters ``*'', ``?'' or ``[''.
GLOB_NOMAGIC is provided to simplify implementing the historic
csh(1) globbing behavior and should probably not be used anywhere else.
GLOB_NOESCAPE
Disable the use of the backslash (‘\') character for quoting.
GLOB_TILDE
Expand patterns that start with ‘~' to user name home directories.
GLOB_LIMIT
Limit the amount of memory used to store matched strings to
64K, the number of
stat(2) calls to 128, and the number of
readdir(3) calls to 16K. This option should be set for programs that can be coerced to a denial of service attack via patterns that expand to a very large number of matches, such as a long string of
*/../*/..
GLOB_PERIOD
Allow metacharacters to match a leading period in a filename.
GLOB_NO_DOTDIRS
Hide ‘.' and ‘..' from metacharacter matches, regardless of whether GLOB_PERIOD is set and whether the pattern component begins with a literal period. GLOB_STAR Indicates that two adjacent * characters will do a recursive match in all subdirs, without following symbolic links and three adjacent * characters will also follow symbolic links.
If, during the search, a directory is encountered that cannot be opened or read and
errfunc is non-
NULL,
glob() calls
(*errfunc)(path, errno). This may be unintuitive: a pattern like ‘*/Makefile' will try to
stat(2) ‘foo/Makefile' even if ‘foo' is not a directory, resulting in a call to
errfunc. The error routine can suppress this action by testing for
ENOENT and
ENOTDIR; however, the
GLOB_ERR flag will still cause an immediate return when this happens.
If
errfunc returns non-zero,
glob() stops the scan and returns
GLOB_ABORTED after setting
gl_pathc and
gl_pathv to reflect any paths already matched. This also happens if an error is encountered and
GLOB_ERR is set in
flags, regardless of the return value of
errfunc, if called. If
GLOB_ERR is not set and either
errfunc is
NULL or
errfunc returns zero, the error is ignored.
The
globfree() function frees any space associated with
pglob from a previous call(s) to
glob().
The
glob_pattern_p() returns
1 if the
pattern has any special characters that
glob() will interpret and
0 otherwise. If the
quote argument is non-zero, then backslash quoted characters are ignored.
The historical
GLOB_QUOTE flag is no longer supported. Per IEEE Std 1003.2-1992 (“POSIX.2”), backslash escaping of special characters is the default behaviour; it may be disabled by specifying the
GLOB_NOESCAPE flag.