endmntent(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 *stream);

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

   int endmntent(FILE *streamp);

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

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

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

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

   getmntent_r():
       Since glibc 2.19:
           _DEFAULT_SOURCE
       Glibc 2.19 and earlier:
           _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  of  the  filesystem
   description  file  from  stream  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 stream.

   The   endmntent()  function  closes  the  stream  associated  with  the
   filesystem description file.

   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 backslash (\134) in those files when
   they occur in one of the four  strings  in  a  mntent  structure.   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

ATTRIBUTES

   For  an  explanation  of  the  terms  used   in   this   section,   see
   attributes(7).

   ┌──────────────┬───────────────┬─────────────────────────────────┐
   │Interface     │ Attribute     │ Value                           │
   ├──────────────┼───────────────┼─────────────────────────────────┤
   │setmntent(),  │ Thread safety │ MT-Safe                         │
   │endmntent(),  │               │                                 │
   │hasmntopt()   │               │                                 │
   ├──────────────┼───────────────┼─────────────────────────────────┤
   │getmntent()   │ Thread safety │ MT-Unsafe race:mntentbuf locale │
   ├──────────────┼───────────────┼─────────────────────────────────┤
   │addmntent()   │ Thread safety │ MT-Safe race:stream locale      │
   ├──────────────┼───────────────┼─────────────────────────────────┤
   │getmntent_r() │ Thread safety │ MT-Safe locale                  │
   └──────────────┴───────────────┴─────────────────────────────────┘

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 4.09 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
   https://www.kernel.org/doc/man-pages/.

                              2016-03-15                      GETMNTENT(3)

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