glob, globfree - generate pathnames matching a pattern
#include <glob.h> int glob(const char *pattern, int flags, int(*errfunc)(const char *epath, int errno), glob_t *pglob); void globfree(glob_t *pglob);
The glob() function is a pathname generator that implements the rules defined in the XCU specification, Section 2.13, Pattern Matching Notation, with optional support for rule 3 in the XCU specification, Section 2.13.3, Patterns Used for Filename Expansion.
The structure type glob_t is defined in the header <glob.h> and includes at least the following members:
Member Type Member Name Description size_t gl_pathc Count of paths matched by pattern. char ** gl_pathv Pointer to a list of matched pathnames. size_t gl_offs Slots to reserve at the beginning of gl_pathv.
The argument pattern is a pointer to a pathname pattern to be expanded. The glob() function matches all accessible pathnames against this pattern and develops a list of all 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 following special characters:
* ? [
The glob() function stores the number of matched pathnames into pglob->gl_pathc and a pointer to a list of pointers to pathnames into pglob->gl_pathv. The pathnames are in sort order as defined by the current setting of the LC_COLLATE category, see the XBD specification, LC_COLLATE . The first pointer after the last pathname is a null pointer. If the pattern does not match any pathnames, the returned number of matched paths is set to 0, and the contents of pglob->gl_pathv are implementation-dependent.
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 globfree() function frees any space associated with pglob from a previous call to glob().
The flags argument is used to control the behaviour of glob(). The value of flags is a bitwise inclusive OR of zero or more of the following constants, which are defined in the header <glob.h>:
- Append pathnames generated to the ones from a previous call to glob().
- Make use of pglob->gl_offs. If this flag is set, pglob->gl_offs is used to specify how many null pointers to add to the beginning of pglob->gl_pathv. In other words, pglob->gl_pathv will point to null pointers, followed by pathname pointers, followed by a null pointer.
- Causes glob() to return when it encounters a directory that it cannot open or read. Ordinarily, glob() continues to find matches.
- Each pathname that is a directory that matches pattern has a slash appended.
- Support rule 3 in the XCU specification, Section 2.13.3, Patterns Used for Filename Expansion. If pattern does not match any pathname, then glob() returns a list consisting of only pattern, and the number of matched pathnames is 1.
- Disable backslash escaping.
- Ordinarily, glob() sorts the matching pathnames according to the current setting of the LC_COLLATE category, see the XBD specification, LC_COLLATE . When this flag is used the order of pathnames returned is unspecified.
The GLOB_APPEND flag can be used to append a new set of pathnames to those found in a previous call to glob(). The following rules apply when two or more calls to glob() are made with the same value of pglob and without intervening calls to globfree():
- The first such call must not set GLOB_APPEND. All subsequent calls must set it.
- All the calls must set GLOB_DOOFFS, or all must not set it.
- After the second call, pglob->gl_pathv points to a list containing the following:
- Zero or more null pointers, as specified by GLOB_DOOFFS and pglob->gl_offs
- Pointers to the pathnames that were in the pglob->gl_pathv list before the call, in the same order as before.
- Pointers to the new pathnames generated by the second call, in the specified order.
- The count returned in pglob->gl_pathc will be the total number of pathnames from the two calls.
- The application can change any of the fields after a call to glob(). If it does, it must reset them to the original value before a subsequent call, using the same pglob value, to globfree() or glob() with the GLOB_APPEND flag.
If, during the search, a directory is encountered that cannot be opened or read and errfunc is not a null pointer, glob() calls (*errfunc()) with two arguments:
- The epath argument is a pointer to the path that failed.
- The errno argument is the value of errno from the failure, as set by opendir(), readdir() or stat(). (Other values may be used to report other errors not explicitly documented for those functions.)
The following constants are defined as error return values for glob():
- The scan was stopped because GLOB_ERR was set or (*errfunc()) returned non-zero.
- The pattern does not match any existing pathname, and GLOB_NOCHECK was not set in flags.
- An attempt to allocate memory failed.
If (*errfunc)() is called and returns non-zero, or if the GLOB_ERR flag is set in flags, glob() stops the scan and returns GLOB_ABORTED after setting gl_pathc and gl_pathv in pglob to reflect the paths already scanned. If GLOB_ERR is not set and either errfunc is a null pointer or (*errfunc()) returns 0, the error is ignored.
On successful completion, glob() returns 0. The argument pglob->gl_pathc returns the number of matched pathnames and the argument pglob->gl_pathv contains a pointer to a null-terminated list of matched and sorted pathnames. However, if pglob->gl_pathc is 0, the content of pglob->gl_pathv is undefined.
The globfree() function returns no value.
If glob() terminates due to an error, it returns one of the non-zero constants defined in <glob.h>. The arguments pglob->gl_pathc and pglob->gl_pathv are still set as defined above.
No errors are defined.
One use of the GLOB_DOOFFS flag is by applications that build an argument list for use with execv(), execve() or execvp(). Suppose, for example, that an application wants to do the equivalent of:but for some reason:
ls -l *.cis not acceptable. The application could obtain approximately the same result using the sequence:
system("ls -l *.c")
globbuf.gl_offs = 2; glob ("*.c", GLOB_DOOFFS, NULL, &globbuf); globbuf.gl_pathv = "ls"; globbuf.gl_pathv = "-l"; execvp ("ls", &globbuf.gl_pathv);
Using the same example:could be approximately simulated using GLOB_APPEND as follows:
ls -l *.c *.h
globbuf.gl_offs = 2; glob ("*.c", GLOB_DOOFFS, NULL, &globbuf); glob ("*.h", GLOB_DOOFFS|GLOB_APPEND, NULL, &globbuf); ...
This function is not provided for the purpose of enabling utilities to perform pathname expansion on their arguments, as this operation is performed by the shell, and utilities are explicitly not expected to redo this. Instead, it is provided for applications that need to do pathname expansion on strings obtained from other sources, such as a pattern typed by a user or read from a file.
If a utility needs to see if a pathname matches a given pattern, it can use fnmatch().
Note that gl_pathc and gl_pathv have meaning even if glob() fails. This allows glob() to report partial results in the event of an error. However, if gl_pathc is 0, gl_pathv is unspecified even if glob() did not return an error.
The GLOB_NOCHECK option could be used when an application wants to expand a pathname if wildcards are specified, but wants to treat the pattern as just a string otherwise. The sh utility might use this for option-arguments, for example.
The new pathnames generated by a subsequent call with GLOB_APPEND are not sorted together with the previous pathnames. This mirrors the way that the shell handles pathname expansion when multiple expansions are done on a command line.
Applications that need tilde and parameter expansion should use wordexp().
execv(), fnmatch(), opendir(), readdir(), stat(), wordexp(), <glob.h>, the XCU specification.
Derived from the ISO POSIX-2 standard.