glob(3G) glob(3G)
glob - generate pathnames matching a pattern
#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);
The structure type glob_t is defined in the header <glob.h> and includes
at least the following members:
MemberType MemberName Description
_______________________________________________________________
size_t gl_offs Slots to reserve at start of gl_pathv.
char ** gl_pathv Pointer to list of matched pathnames.
size_t gl_pathc Count of paths matched by pattern.
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
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. 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 undetermined.
It is the caller's responsibility to create the structure pointed to by
glob. glob allocates other space as needed, including the memory pointed
to by gl_pathv. The globfree function frees any space associated with
glob 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>:
GLOB_APPEND
Append pathnames generated to the ones from a previous call to glob.
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glob(3G) glob(3G)
GLOB_DOOFFS
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
pglob->gl_offs null pointers, followed by pglob->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, and the number of matched pathnames is
one (1).
GLOB_NOESCAPE
Disable backslash escaping.
GLOB_NOSORT
Ordinarily, glob sorts the matching pathnames according to the
current setting of the LC_COLLATE category. When this flag is used
the order of pathnames returned is unspecified.
GLOB_LIMIT
Limit the amount of memory used by matches to {ARG_MAX} [see
sysconf(2)]. 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.
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
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glob(3G) glob(3G)
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 eerrno argument is the value of errno from that 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:
GLOB_ABORTED
The scan was stopped because GLOB_ERR was set or (*errfunc())
returned non-zero.
GLOB_NOMATCH
The pattern does not match any existing pathname, and GLOB_NOCHECK
was not set in flags.
GLOB_NOSPACE
An attempt to allocate memory failed, or if errno was 0, GLOB_LIMIT
was specified in the flags and the amount of memory required for the
matched patterns exceeded {ARG_MAX}.
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_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.
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glob(3G) glob(3G)
On successful completion, glob returns zero. 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 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.
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:
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";
execp ("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);
...
This function is not provided for the purpose of enabling utilities to
perform pathname expansion on their arguments, as the 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.
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glob(3G) glob(3G)
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 sh utility might use this for optionarguments,
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 sheel handles pathname expansion when multiple expansions are done on
a command line.
Applications that need tilde and parameter expansion should use wordexp.
execv(2), fnmatch(3g), opendir(3b), readdir(3b), stat(2), wordexp(3g),
<glob.h>.
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