GETMNTENT(3)                        Linux Programmer's Manual                        GETMNTENT(3)



NAME
       getmntent,  setmntent,  addmntent,  endmntent,  hasmntopt,  getmntent_r  -  get filesystem
       descriptor file entry

SYNOPSIS
       #include <stdio.h>
       #include <mntent.h>

       FILE *setmntent(const char *filename, const char *type);

       struct mntent *getmntent(FILE *fp);

       int addmntent(FILE *fp, const struct mntent *mnt);

       int endmntent(FILE *fp);

       char *hasmntopt(const struct mntent *mnt, const char *opt);

       /* GNU extension */
       #include <mntent.h>

       struct mntent *getmntent_r(FILE *fp, struct mntent *mntbuf,
                                  char *buf, int buflen);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getmntent_r(): _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION
       These routines are used to access the  filesystem  description  file  /etc/fstab  and  the
       mounted filesystem description file /etc/mtab.

       The setmntent() function opens the filesystem description file filename and returns a file
       pointer which can be used by getmntent().   The  argument  type  is  the  type  of  access
       required and can take the same values as the mode argument of fopen(3).

       The  getmntent()  function reads the next line from the filesystem description file fp and
       returns a pointer to a structure containing the broken out fields from a line in the file.
       The  pointer points to a static area of memory which is overwritten by subsequent calls to
       getmntent().

       The addmntent() function adds the mntent structure mnt to the end of the open file fp.

       The endmntent() function closes the filesystem description file fp.

       The hasmntopt() function scans the mnt_opts field (see below) of the mntent structure  mnt
       for a substring that matches opt.  See <mntent.h> and mount(8) for valid mount options.

       The  reentrant  getmntent_r()  function  is  similar to getmntent(), but stores the struct
       mount in the provided *mntbuf and stores the strings pointed to by  the  entries  in  that
       struct in the provided array buf of size buflen.

       The mntent structure is defined in <mntent.h> as follows:

           struct mntent {
               char *mnt_fsname;   /* name of mounted filesystem */
               char *mnt_dir;      /* filesystem path prefix */
               char *mnt_type;     /* mount type (see mntent.h) */
               char *mnt_opts;     /* mount options (see mntent.h) */
               int   mnt_freq;     /* dump frequency in days */
               int   mnt_passno;   /* pass number on parallel fsck */
           };

       Since  fields  in  the mtab and fstab files are separated by whitespace, octal escapes are
       used to represent the four characters space (\040), tab (\011), newline (\012)  and  back‐
       slash  (\134) in those files when they occur in one of the four strings in a mntent struc‐
       ture.  The routines addmntent() and getmntent() will convert from string representation to
       escaped representation and back.

RETURN VALUE
       The  getmntent()  and  getmntent_r() functions return a pointer to the mntent structure or
       NULL on failure.

       The addmntent() function returns 0 on success and 1 on failure.

       The endmntent() function always returns 1.

       The hasmntopt() function returns the address of the substring if a match is found and NULL
       otherwise.

FILES
       /etc/fstab          filesystem description file
       /etc/mtab           mounted filesystem description file

CONFORMING TO
       The  nonreentrant  functions are from SunOS 4.1.3.  A routine getmntent_r() was introduced
       in HP-UX 10, but it returns an int.  The prototype shown above is glibc-only.

NOTES
       System V also has a getmntent()  function  but  the  calling  sequence  differs,  and  the
       returned  structure is different.  Under System V /etc/mnttab is used.  4.4BSD and Digital
       UNIX have a routine getmntinfo(), a wrapper around the system call getfsstat().

SEE ALSO
       fopen(3), fstab(5), mount(8)

COLOPHON
       This page is part of release 3.74 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at http://www.kernel.org/doc/man-pages/.



                                            2009-09-15                               GETMNTENT(3)