glob

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



PROLOG
       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
       glob, globfree — generate pathnames matching a pattern

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 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.

RETURN VALUE
       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.

ERRORS
       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.

EXAMPLES
       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);
           ...

APPLICATION USAGE
       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().

RATIONALE
       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.

FUTURE DIRECTIONS
       None.

SEE ALSO
       exec, fdopendir(), fnmatch(), fstatat(), readdir(), Section 2.6, Word
       Expansions

       The Base Definitions volume of POSIX.1‐2008, Section 7.3.2, LC_COLLATE,
       <glob.h>

COPYRIGHT
       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(3POSIX)