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

6       getmntent,  setmntent,  addmntent,  endmntent, hasmntopt, getmntent_r -
7       get filesystem descriptor file entry
8

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 *stream);
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17       int addmntent(FILE *stream, const struct mntent *mnt);
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19       int endmntent(FILE *streamp);
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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>
25
26       struct mntent *getmntent_r(FILE *streamp, struct mntent *mntbuf,
27                                  char *buf, int buflen);
28
29   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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31       getmntent_r():
32           Since glibc 2.19:
33               _DEFAULT_SOURCE
34           Glibc 2.19 and earlier:
35               _BSD_SOURCE || _SVID_SOURCE
36

DESCRIPTION

38       These routines are used  to  access  the  filesystem  description  file
39       /etc/fstab and the mounted filesystem description file /etc/mtab.
40
41       The setmntent() function opens the filesystem description file filename
42       and returns a file pointer which can be used by getmntent().  The argu‐
43       ment  type  is the type of access required and can take the same values
44       as the mode argument of fopen(3).
45
46       The getmntent() function reads the next line of the filesystem descrip‐
47       tion  file  from stream and returns a pointer to a structure containing
48       the broken out fields from a line in the file.  The pointer points to a
49       static area of memory which is overwritten by subsequent calls to getm‐
50       ntent().
51
52       The addmntent() function adds the mntent structure mnt to  the  end  of
53       the open stream.
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55       The endmntent() function closes the stream associated with the filesys‐
56       tem description file.
57
58       The hasmntopt() function scans the mnt_opts field (see  below)  of  the
59       mntent  structure mnt for a substring that matches opt.  See <mntent.h>
60       and mount(8) for valid mount options.
61
62       The reentrant getmntent_r() function is  similar  to  getmntent(),  but
63       stores  the struct mount in the provided *mntbuf and stores the strings
64       pointed to by the entries in that struct in the provided array  buf  of
65       size buflen.
66
67       The mntent structure is defined in <mntent.h> as follows:
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69           struct mntent {
70               char *mnt_fsname;   /* name of mounted filesystem */
71               char *mnt_dir;      /* filesystem path prefix */
72               char *mnt_type;     /* mount type (see mntent.h) */
73               char *mnt_opts;     /* mount options (see mntent.h) */
74               int   mnt_freq;     /* dump frequency in days */
75               int   mnt_passno;   /* pass number on parallel fsck */
76           };
77
78       Since  fields  in the mtab and fstab files are separated by whitespace,
79       octal escapes are used to represent the characters  space  (\040),  tab
80       (\011),  newline  (\012),  and  backslash (\\) in those files when they
81       occur in one of the four strings in a mntent structure.   The  routines
82       addmntent()  and getmntent() will convert from string representation to
83       escaped representation and back.  When converting from  escaped  repre‐
84       sentation, the sequence \134 is also converted to a backslash.
85

RETURN VALUE

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

98       /etc/fstab
99              filesystem description file
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101       /etc/mtab
102              mounted filesystem description file
103

ATTRIBUTES

105       For   an   explanation   of   the  terms  used  in  this  section,  see
106       attributes(7).
107
108       ┌──────────────┬───────────────┬─────────────────────────────────┐
109Interface     Attribute     Value                           
110       ├──────────────┼───────────────┼─────────────────────────────────┤
111setmntent(),  │ Thread safety │ MT-Safe                         │
112endmntent(),  │               │                                 │
113hasmntopt()   │               │                                 │
114       ├──────────────┼───────────────┼─────────────────────────────────┤
115getmntent()   │ Thread safety │ MT-Unsafe race:mntentbuf locale │
116       ├──────────────┼───────────────┼─────────────────────────────────┤
117addmntent()   │ Thread safety │ MT-Safe race:stream locale      │
118       ├──────────────┼───────────────┼─────────────────────────────────┤
119getmntent_r() │ Thread safety │ MT-Safe locale                  │
120       └──────────────┴───────────────┴─────────────────────────────────┘

CONFORMING TO

122       The nonreentrant functions are from  SunOS  4.1.3.   A  routine  getmn‐
123       tent_r() was introduced in HP-UX 10, but it returns an int.  The proto‐
124       type shown above is glibc-only.
125

NOTES

127       System V also has a getmntent() function but the calling sequence  dif‐
128       fers,  and  the  returned  structure  is  different.   Under  System  V
129       /etc/mnttab is used.  4.4BSD and Digital  UNIX  have  a  routine  getm‐
130       ntinfo(), a wrapper around the system call getfsstat().
131

SEE ALSO

133       fopen(3), fstab(5), mount(8)
134

COLOPHON

136       This  page  is  part of release 4.16 of the Linux man-pages project.  A
137       description of the project, information about reporting bugs,  and  the
138       latest     version     of     this    page,    can    be    found    at
139       https://www.kernel.org/doc/man-pages/.
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143                                  2017-09-15                      GETMNTENT(3)
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