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GLOB(3P) POSIX Programmer's Manual GLOB(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
glob, globfree — generate pathnames matching a pattern
#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);
The glob() function is a pathname generator that shall implement the
rules defined in the Shell and Utilities volume of POSIX.1‐2008,
Section 2.13, Pattern Matching Notation, with optional support for
rule 3 in the Shell and Utilities volume of POSIX.1‐2008, 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.1‐2008, 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.1‐2008, 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.1‐2008, 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.
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.
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.
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);
...
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().
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.
None.
exec(1p), fdopendir(3p), fnmatch(3p), fstatat(3p), readdir(3p),
Section 2.6, Word Expansions
The Base Definitions volume of POSIX.1‐2008, Section 7.3.2,
LC_COLLATE, glob.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/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 .
IEEE/The Open Group 2013 GLOB(3P)
Pages that refer to this page: glob.h(0p), fnmatch(3p), regcomp(3p), wordexp(3p)
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