glob(S)

glob, globfree -- generate pathnames matching a pattern

Synopsis

   #include <glob.h>
   
   int glob(const char *pattern, int flags,
      int (*errfunc)(const char *epath, int eerrno), glob_t *pglob);
   

   void globfree(glob_t *pglob);

Description

glob is a pathname generator.

The structure type glob_t is defined in the header <glob_h>.

pattern is a pointer to a pathname pattern to be expanded. glob 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:

       *    ?    [

glob 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. 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 zero, and the contents of pglob-> gl_pathv are undefined.

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 behavior 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>:

GLOB_APPEND: Append newly formed pathnames to previously obtained ones
GLOB_DOOFFS: A specification of the number of null pointers that should be added to the start of pglob-> gl_pathv
GLOB_ERR: This is to ensure that if an error occurs, glob is returned
GLOB_MARK: A slash is appended to each directory pathname matching pattern
GLOB_NOCHECK: If there is no match between a pathname and pattern then a list is returned which contains pattern only
GLOB_NOESCAPE: disable backslash escaping
GLOB_NOSORT: Pathnames that are returned are not to be sorted

GLOB_APPEND 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.

1.

The first such call must not set GLOB_APPEND. All subsequent calls must set it.

2.

All the calls must set GLOB_DOOFFS, or all must not set it.

3.

After the second call, pglob-> gl_pathv points to a list containing the following:

a.: Zero or more null pointers, as specified by GLOB_DOOFFS and pglob-> gl_offs.
b.: Pointers to the pathnames that were in the pglob-> gl_pathv list before the call, in the same order as before.
c.: Pointers to the new pathnames generated by the second call, in the specified order.

4.

The count returned in pglob-> gl_pathc will be the total number of pathnames from the two calls.

5.

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:

1.: The epath argument is a pointer to the path that failed.
2.: The eerrno argument is the value of errno from the failure, as set by the opendir, readdir or stat functions. (Other values may be used to report other errors not explicitly documented for those functions.)

Return values

On successful completion, glob returns zero. The argument pglob-> gl_pathv returns the number of matched pathnames and the argument pglob-> gl_pathw contains a pointer to a null-terminated list of matched and sorted pathnames. However, if pglob-> gl_pathc is zero, the contents 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.

Errors

The following constants are defined as error return values for glob:

GLOB_ABORTED: Because (*errfunc) returned zero or GLOB_ERR was set, scanning was terminated.
GLOB_NOMATCH: There is no match between the pattern and any pathname that exists. GLOB_NOCHECK was not set in flags.
GLOB_NOSPACE: Memory allocation failure

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 zero, the error is ignored.

Usage

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 zero, 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 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.

Examples

One use of the GLOB_DOOFFS flag is by applications that build an argument list for use with the execv, execve, or execvp functions. Suppose, for example, that an application wants to do the equivalent of:

   ls -l *.c

but for some reason:

   system("ls -l *.c")

is not acceptable. The application could obtain approximately the same result using the sequence:

   globbuf.gl_offs = 2;
   glob ("*.c", GLOB_DOOFFS, NULL, &globbuf);
   globbuf.gl_pathv[0] = "ls";
   globbuf.gl_pathv[1] = "-l";
   execvp ("ls", &globbuf.gl_pathv[0]);

Using the same example:

   ls -l *.c *.h

could be approximately simulated using GLOB_APPEND as follows:

   globbuf.gl_offs = 2;
   glob ("*.c", GLOB_DOOFFS, NULL, &globbuf);
   glob ("*.h", GLOB_DOOFFS|GLOB_APPEND, NULL, &globbuf);
    ...

References

glob(M), fnmatch(S), stat(S).