glob, globfree — find pathnames matching a pattern, free memory from glob()
#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 searches
for all the pathnames matching pattern according to the rules
used by the shell (see glob(7)). No tilde
expansion or parameter substitution is done; if you want
these, use wordexp(3).
The globfree() function
frees the dynamically allocated storage from an earlier call
to glob().
The results of a glob() call
are stored in the structure pointed to by pglob. This structure is of
type glob_t (declared in
<glob.h> and
includes the following elements defined by POSIX.2 (more may
be present as an extension):
| typedef | struct { | |||
| size_t | gl_pathc; |
/* Count of paths matched so far */
|
||
| char | ** | gl_pathv; |
/* List of matched pathnames. */
|
|
| size_t | gl_offs; |
/* Slots to reserve in gl_pathv. */
|
||
| } glob_t; | ||||
Results are stored in dynamically allocated storage.
The argument flags
is made up of the bitwise OR of zero or more the following
symbolic constants, which modify the behavior of glob():
GLOB_ERRReturn upon a read error (because a directory does
not have read permission, for example). By default,
glob() attempts carry on
despite errors, reading all of the directories that it
can.
GLOB_MARKAppend a slash to each path which corresponds to a directory.
GLOB_NOSORTDon't sort the returned pathnames. The only reason to do this is to save processing time. By default, the returned pathnames are sorted.
GLOB_DOOFFSReserve pglob−>gl_offs
slots at the beginning of the list of strings in
pglob−>pathv.
The reserved slots contain null pointers.
GLOB_NOCHECKIf no pattern matches, return the original pattern.
By default, glob()
returns GLOB_NOMATCH if
there are no matches.
GLOB_APPENDAppend the results of this call to the vector of
results returned by a previous call to glob(). Do not set this flag on the
first invocation of glob().
GLOB_NOESCAPEDon't allow backslash ('\') to be used as an escape character. Normally, a backslash can be used to quote the following character, providing a mechanism to turn off the special meaning metacharacters.
flags may also
include any of the following, which are GNU extensions and
not defined by POSIX.2:
GLOB_PERIODAllow a leading period to be matched by metacharacters. By default, metacharacters can't match a leading period.
GLOB_ALTDIRFUNCUse alternative functions pglob−>gl_closedir,
pglob−>gl_readdir,
pglob−>gl_opendir,
pglob−>gl_lstat,
and pglob−>gl_stat
for filesystem access instead of the normal library
functions.
GLOB_BRACEExpand csh(1) style brace
expressions of the form {a,b}. Brace
expressions can be nested. Thus, for example,
specifying the pattern "{foo/{,cat,dog},bar}" would
return the same results as four separate glob() calls using the strings:
"foo/", "foo/cat", "foo/dog", and "bar".
GLOB_NOMAGICIf the pattern contains no metacharacters, then it should be returned as the sole matching word, even if there is no file with that name.
GLOB_TILDECarry out tilde expansion. If a tilde ('~') is the only character in the pattern, or an initial tilde is followed immediately by a slash ('/'), then the home directory of the caller is substituted for the tilde. If an initial tilde is followed by a username (e.g., "~andrea/bin"), then the tilde and username are substituted by the home directory of that user. If the username is invalid, or the home directory cannot be determined, then no substitution is performed.
GLOB_TILDE_CHECKThis provides behavior similar to that of
GLOB_TILDE. The
difference is that if the username is invalid, or the
home directory cannot be determined, then instead of
using the pattern itself as the name, glob() returns GLOB_NOMATCH to indicate an
error.
GLOB_ONLYDIRThis is a hint to glob() that the caller is interested
only in directories that match the pattern. If the
implementation can easily determine file-type
information, then nondirectory files are not returned
to the caller. However, the caller must still check
that returned files are directories. (The purpose of
this flag is merely to optimize performance when the
caller is interested only in directories.)
If errfunc is not
NULL, it will be called in case of an error with the
arguments epath, a
pointer to the path which failed, and eerrno, the value of errno as returned from one of the calls to
opendir(3), readdir(3), or stat(2). If errfunc returns nonzero, or if
GLOB_ERR is set, glob() will terminate after the call to
errfunc.
Upon successful return, pglob−>gl_pathc
contains the number of matched pathnames and pglob−>gl_pathv
contains a pointer to the list of pointers to matched
pathnames. The list of pointers is terminated by a null
pointer.
It is possible to call glob() several times. In that case, the
GLOB_APPEND flag has to be set
in flags on the
second and later invocations.
As a GNU extension, pglob−>gl_flags is
set to the flags specified, ored with GLOB_MAGCHAR if any metacharacters were
found.
On successful completion, glob() returns zero. Other possible returns
are:
GLOB_NOSPACEfor running out of memory,
GLOB_ABORTEDfor a read error, and
GLOB_NOMATCHfor no found matches.
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
glob() |
Thread safety | MT-Unsafe race:utent env sig:ALRM timer locale |
globfree() |
Thread safety | MT-Safe |
In the above table, utent in
race:utent
signifies that if any of the functions setutent(3), getutent(3), or endutent(3) are used in
parallel in different threads of a program, then data races
could occur. glob() calls those
functions, so we use race:utent to remind users.
The structure elements gl_pathc and gl_offs are declared as
size_t in glibc 2.1, as they should
be according to POSIX.2, but are declared as int in glibc 2.0.
The glob() function may fail
due to failure of underlying function calls, such as
malloc(3) or opendir(3). These will
store their error code in errno.
One example of use is the following code, which simulates typing
ls −l *.c ../*.c
in the shell:
glob_t globbuf;
globbuf.gl_offs = 2;
glob("*.c", GLOB_DOOFFS, NULL, &globbuf);
glob("../*.c", GLOB_DOOFFS | GLOB_APPEND, NULL, &globbuf);
globbuf.gl_pathv[0] = "ls";
globbuf.gl_pathv[1] = "−l";
execvp("ls", &globbuf.gl_pathv[0]);
ls(1), sh(1), stat(2), exec(3), fnmatch(3), malloc(3), opendir(3), readdir(3), wordexp(3), glob(7)