Manpage of GLOB


Section: Linux Programmer's Manual (3)
Updated: 2016-10-08


glob, globfree - find pathnames matching a pattern, free memory from glob()  


#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 glob() function searches for all the pathnames matching patternaccording 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 flagsis made up of the bitwise OR of zero or more the following symbolic constants, which modify the behavior of glob():

Return 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.
Append a slash to each path which corresponds to a directory.
Don't sort the returned pathnames. The only reason to do this is to save processing time. By default, the returned pathnames are sorted.
Reserve pglob->gl_offsslots at the beginning of the list of strings in pglob->pathv. The reserved slots contain null pointers.
If no pattern matches, return the original pattern. By default, glob() returns GLOB_NOMATCHif there are no matches.
Append 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().
Don't allow backslash (aq\aq) 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.

flagsmay also include any of the following, which are GNU extensions and not defined by POSIX.2:

Allow a leading period to be matched by metacharacters. By default, metacharacters can't match a leading period.
Use alternative functions pglob->gl_closedir, pglob->gl_readdir, pglob->gl_opendir, pglob->gl_lstat, and pglob->gl_statfor filesystem access instead of the normal library functions.
Expand 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".
If the pattern contains no metacharacters, then it should be returned as the sole matching word, even if there is no file with that name.
Carry out tilde expansion. If a tilde (aq~aq) is the only character in the pattern, or an initial tilde is followed immediately by a slash (aq/aq), 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.
This 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_NOMATCHto indicate an error.
This is a hintto 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 errfuncis 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 errnoas returned from one of the calls to opendir(3), readdir(3), or stat(2). If errfuncreturns nonzero, or if GLOB_ERRis set, glob() will terminate after the call to errfunc.

Upon successful return, pglob->gl_pathccontains the number of matched pathnames and pglob->gl_pathvcontains 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_APPENDflag has to be set in flagson the second and later invocations.

As a GNU extension, pglob->gl_flagsis set to the flags specified, ored with GLOB_MAGCHARif any metacharacters were found.  


On successful completion, glob() returns zero. Other possible returns are:
for running out of memory,
for a read error, and
for no found matches.


For an explanation of the terms used in this section, see attributes(7).
glob() Thread safetyMT-Unsafe race:utent env
sig:ALRM timer locale
globfree() Thread safetyMT-Safe

In the above table, utentin race:utentsignifies 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.  


POSIX.1-2001, POSIX.1-2008, POSIX.2.  


The structure elements gl_pathcand gl_offsare declared as size_tin glibc 2.1, as they should be according to POSIX.2, but are declared as intin 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)




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