NAME

       getmntent,  setmntent,  addmntent,  endmntent,  hasmntopt,  getmntent_r  -  get filesystem
       descriptor file entry

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <stdio.h>
       #include <mntent.h>

       FILE *setmntent(const char *filename, const char *type);

       struct mntent *getmntent(FILE *stream);

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

       int endmntent(FILE *streamp);

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

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

       struct mntent *getmntent_r(FILE *restrict streamp,
                     struct mntent *restrict mntbuf,
                     char buf[restrict .buflen], 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 returned
       stream should be closed using endmntent() rather than fclose(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 mntent
       structure in the provided *mntbuf, and stores the strings pointed to  by  the  entries  in
       that structure 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).

       ┌─────────────────────────┬───────────────┬───────────────────────────────────────────────┐
       │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                                │
       └─────────────────────────┴───────────────┴───────────────────────────────────────────────┘

STANDARDS

       None.

HISTORY

       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.

       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)