1GETMNTENT(3)               Linux Programmer's Manual              GETMNTENT(3)
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NAME

6       getmntent,  setmntent,  addmntent,  endmntent, hasmntopt, getmntent_r -
7       get file system descriptor file entry
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SYNOPSIS

10       #include <stdio.h>
11       #include <mntent.h>
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13       FILE *setmntent(const char *filename, const char *type);
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15       struct mntent *getmntent(FILE *fp);
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17       int addmntent(FILE *fp, const struct mntent *mnt);
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19       int endmntent(FILE *fp);
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21       char *hasmntopt(const struct mntent *mnt, const char *opt);
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23       /* GNU extension */
24       #include <mntent.h>
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26       struct mntent *getmntent_r(FILE *fp, struct mntent *mntbuf,
27                                  char *buf, int buflen);
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29   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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31       getmntent_r(): _BSD_SOURCE || _SVID_SOURCE
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DESCRIPTION

34       These routines are used to access  the  file  system  description  file
35       /etc/fstab and the mounted file system description file /etc/mtab.
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37       The  setmntent()  function opens the file system description file file‐
38       name and returns a file pointer which can be used by getmntent().   The
39       argument type is the type of access required and can take the same val‐
40       ues as the mode argument of fopen(3).
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42       The getmntent() function reads the  next  line  from  the  file  system
43       description file fp and returns a pointer to a structure containing the
44       broken out fields from a line in the file.  The  pointer  points  to  a
45       static area of memory which is overwritten by subsequent calls to getm‐
46       ntent().
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48       The addmntent() function adds the mntent structure mnt to  the  end  of
49       the open file fp.
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51       The endmntent() function closes the file system description file fp.
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53       The  hasmntopt()  function  scans the mnt_opts field (see below) of the
54       mntent structure mnt for a substring that matches opt.  See  <mntent.h>
55       and mount(8) for valid mount options.
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57       The  reentrant  getmntent_r()  function  is similar to getmntent(), but
58       stores the struct mount in the provided *mntbuf and stores the  strings
59       pointed  to  by the entries in that struct in the provided array buf of
60       size buflen.
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62       The mntent structure is defined in <mntent.h> as follows:
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64           struct mntent {
65               char *mnt_fsname;   /* name of mounted file system */
66               char *mnt_dir;      /* file system path prefix */
67               char *mnt_type;     /* mount type (see mntent.h) */
68               char *mnt_opts;     /* mount options (see mntent.h) */
69               int   mnt_freq;     /* dump frequency in days */
70               int   mnt_passno;   /* pass number on parallel fsck */
71           };
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73       Since fields in the mtab and fstab files are separated  by  whitespace,
74       octal  escapes  are used to represent the four characters space (\040),
75       tab (\011), newline (\012) and backslash (\134)  in  those  files  when
76       they  occur in one of the four strings in a mntent structure.  The rou‐
77       tines addmntent() and getmntent() will convert from string  representa‐
78       tion to escaped representation and back.
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RETURN VALUE

81       The  getmntent()  and  getmntent_r()  functions return a pointer to the
82       mntent structure or NULL on failure.
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84       The addmntent() function returns 0 on success and 1 on failure.
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86       The endmntent() function always returns 1.
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88       The hasmntopt() function returns the address  of  the  substring  if  a
89       match is found and NULL otherwise.
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FILES

92       /etc/fstab          file system description file
93       /etc/mtab           mounted file system description file
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CONFORMING TO

96       The  nonreentrant  functions  are  from  SunOS 4.1.3.  A routine getmn‐
97       tent_r() was introduced in HP-UX 10, but it returns an int.  The proto‐
98       type shown above is glibc-only.
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NOTES

101       System  V also has a getmntent() function but the calling sequence dif‐
102       fers,  and  the  returned  structure  is  different.   Under  System  V
103       /etc/mnttab  is  used.   4.4BSD  and  Digital Unix have a routine getm‐
104       ntinfo(), a wrapper around the system call getfsstat().
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SEE ALSO

107       fopen(3), fstab(5), mount(8)
108

COLOPHON

110       This page is part of release 3.25 of the Linux  man-pages  project.   A
111       description  of  the project, and information about reporting bugs, can
112       be found at http://www.kernel.org/doc/man-pages/.
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116                                  2009-09-15                      GETMNTENT(3)
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