glob(3p) — Linux manual page


GLOB(3P)                POSIX Programmer's Manual               GLOB(3P)

PROLOG         top

       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.

NAME         top

       glob, globfree — generate pathnames matching a pattern

SYNOPSIS         top

       #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         top

       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

       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

       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

        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         top

       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

       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

ERRORS         top

       The glob() function shall fail and return the corresponding value

       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         top

       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

RATIONALE         top

       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 *));
           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.



SEE ALSO         top

       exec(1p), fdopendir(3p), fnmatch(3p), fstatat(3p), readdir(3p),
       Section 2.6, Word Expansions

       The Base Definitions volume of POSIX.1‐2017, Section 7.3.2,
       LC_COLLATE, glob.h(0p)

COPYRIGHT         top

       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 .

       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 .

IEEE/The Open Group               2017                          GLOB(3P)

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