addmntent

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 *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 argu-
       ment  type  is the type of access required and can take the same values
       as the mode argument of fopen(3).  The returned stream should be closed
       using endmntent() rather than fclose(3).

       The getmntent() function reads the next line of the filesystem descrip-
       tion 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 getm-
       ntent().

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

       The endmntent() function closes the stream associated with the filesys-
       tem 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 oc-
       cur in one of the four strings in a mntent structure.  The routines ad-
       dmntent() and getmntent() will convert from  string  representation  to
       escaped  representation  and back.  When converting from escaped repre-
       sentation, the sequence \134 is also converted to a backslash.

RETURN VALUE
       The getmntent() and getmntent_r() functions return a pointer to the mn-
       tent 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  at-
       tributes(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 getmn-
       tent_r() was introduced in HP-UX 10, but it returns an int.  The proto-
       type shown above is glibc-only.

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

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

COLOPHON
       This page is part of release 5.05 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/.

                                  2019-03-06                      GETMNTENT(3)