Beside the flags described in the last section, the GNU implementation of
glob allows a few more flags which are also defined in the
glob.h file. Some of the extensions implement functionality
which is available in modern shell implementations.
The . character (period) is treated special. It cannot be
matched by wildcards. See Wildcard Matching, FNM_PERIOD.
The GLOB_MAGCHAR value is not to be given to glob in the
flags parameter. Instead, glob sets this bit in the
gl_flags element of the glob_t structure provided as the
result if the pattern used for matching contains any wildcard character.
Instead of the using the using the normal functions for accessing the
filesystem the glob implementation uses the user-supplied
functions specified in the structure pointed to by pglob
parameter. For more information about the functions refer to the
sections about directory handling see Accessing Directories, and
If this flag is given the handling of braces in the pattern is changed.
It is now required that braces appear correctly grouped. I.e., for each
opening brace there must be a closing one. Braces can be used
recursively. So it is possible to define one brace expression in
another one. It is important to note that the range of each brace
expression is completely contained in the outer brace expression (if
there is one).
The string between the matching braces is separated into single
expressions by splitting at , (comma) characters. The commas
themselves are discarded. Please note what we said above about recursive
brace expressions. The commas used to separate the subexpressions must
be at the same level. Commas in brace subexpressions are not matched.
They are used during expansion of the brace expression of the deeper
level. The example below shows this
If the pattern contains no wildcard constructs (it is a literal file name),
return it as the sole “matching” word, even if no file exists by that name.
If this flag is used the character ~ (tilde) is handled special
if it appears at the beginning of the pattern. Instead of being taken
verbatim it is used to represent the home directory of a known user.
If ~ is the only character in pattern or it is followed by a
/ (slash), the home directory of the process owner is
substituted. Using getlogin and getpwnam the information
is read from the system databases. As an example take user bart
with his home directory at /home/bart. For him a call like
glob ("~/bin/*", GLOB_TILDE, NULL, &result)
would return the contents of the directory /home/bart/bin.
Instead of referring to the own home directory it is also possible to
name the home directory of other users. To do so one has to append the
user name after the tilde character. So the contents of user
homer's bin directory can be retrieved by
glob ("~homer/bin/*", GLOB_TILDE, NULL, &result)
If the user name is not valid or the home directory cannot be determined
for some reason the pattern is left untouched and itself used as the
result. I.e., if in the last example home is not available the
tilde expansion yields to "~homer/bin/*" and glob is not
looking for a directory named ~homer.
This functionality is equivalent to what is available in C-shells if the
nonomatch flag is set.
If this flag is used glob behaves like as if GLOB_TILDE is
given. The only difference is that if the user name is not available or
the home directory cannot be determined for other reasons this leads to
an error. glob will return GLOB_NOMATCH instead of using
the pattern itself as the name.
This functionality is equivalent to what is available in C-shells if
nonomatch flag is not set.
If this flag is used the globbing function takes this as a
hint that the caller is only interested in directories
matching the pattern. If the information about the type of the file
is easily available non-directories will be rejected but no extra
work will be done to determine the information for each file. I.e.,
the caller must still be able to filter directories out.
This functionality is only available with the GNU glob
implementation. It is mainly used internally to increase the
performance but might be useful for a user as well and therefore is
Calling glob will in most cases allocate resources which are used
to represent the result of the function call. If the same object of
type glob_t is used in multiple call to glob the resources
are freed or reused so that no leaks appear. But this does not include
the time when all glob calls are done.
— Function: void globfree (glob_t *pglob)
The globfree function frees all resources allocated by previous
calls to glob associated with the object pointed to by
pglob. This function should be called whenever the currently used
glob_t typed object isn't used anymore.
— Function: void globfree64 (glob64_t *pglob)
This function is equivalent to globfree but it frees records of
type glob64_t which were allocated by glob64.
Published under the terms of the GNU General Public License