GETMNTENT(3)               Linux Programmer's Manual              GETMNTENT(3)
NAME
       getmntent,  setmntent,  addmntent,  endmntent, hasmntopt, getmntent_r -
       get file system 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 */
       #define _GNU_SOURCE    /* or _SVID_SOURCE or _BSD_SOURCE */
       #include <mntent.h>

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

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

       The  setmntent() function opens the file system description file fp 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  file  system
       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 getm-
       ntent().

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

       The endmntent() function closes the file system 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 file system */
                      char    *mnt_dir;       /* file system 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 rou-
       tines addmntent() and getmntent() will convert from string  representa-
       tion 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          file system description file
       /etc/mtab           mounted file system description file

CONFORMING TO
       The  non-reentrant  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.  LSB deprecates the functions endhos-
       tent(), sethostent() and setmntent().

NOTES
       System V also has a getmntent() function but the calling sequence  dif-
       fers, and the returned structure is different. Under System V /etc/mnt-
       tab 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)

                                  2003-11-15                      GETMNTENT(3)