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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 characters space (\040), tab (\011), newline (\012), and backslash
       (\\) 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.  When converting from escaped representation, the  sequence  \134
       is also converted to a backslash.

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).

       ┌──────────────┬───────────────┬─────────────────────────────────┐
       │InterfaceAttributeValue                           │
       ├──────────────┼───────────────┼─────────────────────────────────┤
       │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 4.16 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/.

                                            2017-09-15                               GETMNTENT(3)