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This manual page is part of the POSIX Programmer's Manual. The Linux implementation of
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NAME
glob, globfree — generate pathnames matching a pattern
SYNOPSIS
#include <glob.h>
int glob(const char *restrict pattern, int flags,
int(*errfunc)(const char *epath, int eerrno),
glob_t *restrict pglob);
void globfree(glob_t *pglob);
DESCRIPTION
The glob() function is a pathname generator that shall implement the rules defined in the
Shell and Utilities volume of POSIX.1‐2017, Section 2.13, Pattern Matching Notation, with
optional support for rule 3 in the Shell and Utilities volume of POSIX.1‐2017, Section
2.13.3, Patterns Used for Filename Expansion.
The structure type glob_t is defined in <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 shall match all accessible pathnames against this pattern and develop 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: '*', '?', and '['.
The glob() function shall store 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 shall be in
sort order as defined by the current setting of the LC_COLLATE category; see the Base
Definitions volume of POSIX.1‐2017, Section 7.3.2, LC_COLLATE. The first pointer after
the last pathname shall be 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-defined.
It is the caller's responsibility to create the structure pointed to by pglob. The glob()
function shall allocate other space as needed, including the memory pointed to by
gl_pathv. The globfree() function shall free 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
<glob.h>:
GLOB_APPEND Append pathnames generated to the ones from a previous call to glob().
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 shall point to pglob->gl_offs null pointers,
followed by pglob->gl_pathc pathname pointers, followed by a null pointer.
GLOB_ERR Cause 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 shall have a <slash>
appended.
GLOB_NOCHECK Supports rule 3 in the Shell and Utilities volume of POSIX.1‐2017, Section
2.13.3, Patterns Used for Filename Expansion. If pattern does not match any
pathname, then glob() shall return a list consisting of only pattern, and
the number of matched pathnames is 1.
GLOB_NOESCAPE Disable backslash escaping.
GLOB_NOSORT Ordinarily, glob() sorts the matching pathnames according to the current
setting of the LC_COLLATE category; see the Base Definitions volume of
POSIX.1‐2017, Section 7.3.2, 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 to applications 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 shall not set GLOB_APPEND. All subsequent calls shall set it.
2. All the calls shall set GLOB_DOOFFS, or all shall 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 shall 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, the
application shall 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 opendir(),
readdir(), or stat(). (Other values may be used to report other errors not explicitly
documented for those functions.)
If (()*errfunc ) is called and returns non-zero, or if the GLOB_ERR flag is set in flags,
glob() shall stop the scan and return 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 shall be ignored.
The glob() function shall not fail because of large files.
RETURN VALUE
Upon successful completion, glob() shall return 0. The argument pglob->gl_pathc shall
return the number of matched pathnames and the argument pglob->gl_pathv shall contain 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 shall not return a value.
If glob() terminates due to an error, it shall return 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 glob() function shall fail and return the corresponding value if:
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.
The following sections are informative.
EXAMPLES
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";
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);
...
APPLICATION 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 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().
RATIONALE
It was claimed that the GLOB_DOOFFS flag is unnecessary because it could be simulated
using:
new = (char **)malloc((n + pglob->gl_pathc + 1)
* sizeof(char *));
(void) memcpy(new+n, pglob->gl_pathv,
pglob->gl_pathc * sizeof(char *));
(void) memset(new, 0, n * sizeof(char *));
free(pglob->gl_pathv);
pglob->gl_pathv = new;
However, this assumes that the memory pointed to by gl_pathv is a block that was
separately created using malloc(). This is not necessarily the case. An application
should make no assumptions about how the memory referenced by fields in pglob was
allocated. It might have been obtained from malloc() in a large chunk and then carved up
within glob(), or it might have been created using a different memory allocator. It is not
the intent of the standard developers to specify or imply how the memory used by glob() is
managed.
The GLOB_APPEND flag would be used when an application wants to expand several different
patterns into a single list.
FUTURE DIRECTIONS
None.
SEE ALSO
exec, fdopendir(), fnmatch(), fstatat(), readdir(), Section 2.6, Word Expansions
The Base Definitions volume of POSIX.1‐2017, Section 7.3.2, LC_COLLATE, <glob.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1-2017, Standard for Information Technology -- Portable Operating System Interface
(POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by
the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard is the referee document. The
original Standard can be obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page are most likely to have
been introduced during the conversion of the source files to man page format. To report
such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .