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

NAME

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

LIBRARY

       Standard C library (libc, -lc)

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 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_ERR
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.

GLOB_MARK
Append a slash to each path which corresponds to a directory.

GLOB_NOSORT
Don't sort the returned pathnames. The only reason to do this is to save processing time. By
default, the returned pathnames are sorted.

GLOB_DOOFFS
Reserve pglob->gl_offs slots at the beginning of the list of strings in pglob->pathv. The
reserved slots contain null pointers.

GLOB_NOCHECK
If no pattern matches, return the original pattern. By default, glob() returns GLOB_NOMATCH if
there are no matches.

GLOB_APPEND
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().

GLOB_NOESCAPE
Don'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_PERIOD
Allow a leading period to be matched by metacharacters. By default, metacharacters can't match a
leading period.

GLOB_ALTDIRFUNC
Use 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_BRACE
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".

GLOB_NOMAGIC
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.

GLOB_TILDE
Carry 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_CHECK
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_NOMATCH to indicate an error.

GLOB_ONLYDIR
This 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.

RETURN VALUE

       On successful completion, glob() returns zero.  Other possible returns are:

       GLOB_NOSPACE
              for running out of memory,

       GLOB_ABORTED
              for a read error, and

       GLOB_NOMATCH
              for no found matches.

ATTRIBUTES

       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.

STANDARDS

       POSIX.1-2008.

HISTORY

       POSIX.1-2001, POSIX.2.

NOTES

       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.

BUGS

       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.

EXAMPLES

       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]);