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 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
       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  repre-
       sentation, 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).

       +--------------+---------------+---------------------------------+
       |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 4.15 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)
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