| .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| .\" |
| .\" %%%LICENSE_START(VERBATIM) |
| .\" Permission is granted to make and distribute verbatim copies of this |
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| .\" manual under the conditions for verbatim copying, provided that the |
| .\" entire resulting derived work is distributed under the terms of a |
| .\" permission notice identical to this one. |
| .\" |
| .\" Since the Linux kernel and libraries are constantly changing, this |
| .\" manual page may be incorrect or out-of-date. The author(s) assume no |
| .\" responsibility for errors or omissions, or for damages resulting from |
| .\" the use of the information contained herein. The author(s) may not |
| .\" have taken the same level of care in the production of this manual, |
| .\" which is licensed free of charge, as they might when working |
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| .\" Formatted or processed versions of this manual, if unaccompanied by |
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| .\" %%%LICENSE_END |
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| .\" References consulted: |
| .\" Linux libc source code |
| .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) |
| .\" 386BSD man pages |
| .\" Modified Sat Jul 24 21:46:57 1993 by Rik Faith (faith@cs.unc.edu) |
| .\" Modified 961109, 031115, aeb |
| .\" |
| .TH GETMNTENT 3 2021-03-22 "" "Linux Programmer's Manual" |
| .SH NAME |
| getmntent, setmntent, addmntent, endmntent, hasmntopt, |
| getmntent_r \- get filesystem descriptor file entry |
| .SH SYNOPSIS |
| .nf |
| .B #include <stdio.h> |
| .B #include <mntent.h> |
| .PP |
| .BI "FILE *setmntent(const char *" filename ", const char *" type ); |
| .PP |
| .BI "struct mntent *getmntent(FILE *" stream ); |
| .PP |
| .BI "int addmntent(FILE *restrict " stream , |
| .BI " const struct mntent *restrict " mnt ); |
| .PP |
| .BI "int endmntent(FILE *" streamp ); |
| .PP |
| .BI "char *hasmntopt(const struct mntent *" mnt ", const char *" opt ); |
| .PP |
| /* GNU extension */ |
| .B #include <mntent.h> |
| .PP |
| .BI "struct mntent *getmntent_r(FILE *restrict " streamp , |
| .BI " struct mntent *restrict " mntbuf , |
| .BI " char *restrict " buf ", int " buflen ); |
| .fi |
| .PP |
| .RS -4 |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .RE |
| .PP |
| .BR getmntent_r (): |
| .nf |
| Since glibc 2.19: |
| _DEFAULT_SOURCE |
| Glibc 2.19 and earlier: |
| _BSD_SOURCE || _SVID_SOURCE |
| .fi |
| .SH DESCRIPTION |
| These routines are used to access the filesystem description file |
| .I /etc/fstab |
| and the mounted filesystem description file |
| .IR /etc/mtab . |
| .PP |
| The |
| .BR setmntent () |
| function opens the filesystem description file |
| .I filename |
| and returns a file pointer which can be used by |
| .BR getmntent (). |
| The argument |
| .I type |
| is the type of access |
| required and can take the same values as the |
| .I mode |
| argument of |
| .BR fopen (3). |
| The returned stream should be closed using |
| .BR endmntent () |
| rather than |
| .BR fclose (3). |
| .PP |
| The |
| .BR getmntent () |
| function reads the next line of the filesystem |
| description file from |
| .I 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 |
| .BR getmntent (). |
| .PP |
| The |
| .BR addmntent () |
| function adds the |
| .I mntent |
| structure |
| .I mnt |
| to |
| the end of the open |
| .IR stream . |
| .PP |
| The |
| .BR endmntent () |
| function closes the |
| .IR stream |
| associated with the filesystem description file. |
| .PP |
| The |
| .BR hasmntopt () |
| function scans the |
| .I mnt_opts |
| field (see below) |
| of the |
| .I mntent |
| structure |
| .I mnt |
| for a substring that matches |
| .IR opt . |
| See |
| .I <mntent.h> |
| and |
| .BR mount (8) |
| for valid mount options. |
| .PP |
| The reentrant |
| .BR getmntent_r () |
| function is similar to |
| .BR getmntent (), |
| but stores the |
| .IR "struct mount" |
| in the provided |
| .I *mntbuf |
| and stores the strings pointed to by the entries in that struct |
| in the provided array |
| .I buf |
| of size |
| .IR buflen . |
| .PP |
| The |
| .I mntent |
| structure is defined in |
| .I <mntent.h> |
| as follows: |
| .PP |
| .in +4n |
| .EX |
| 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 */ |
| }; |
| .EE |
| .in |
| .PP |
| Since fields in the mtab and fstab files are separated by whitespace, |
| octal escapes are used to represent the characters space (\e040), |
| tab (\e011), newline (\e012), and backslash (\e\e) in those files |
| when they occur in one of the four strings in a |
| .I mntent |
| structure. |
| The routines |
| .BR addmntent () |
| and |
| .BR getmntent () |
| will convert |
| from string representation to escaped representation and back. |
| When converting from escaped representation, the sequence \e134 is |
| also converted to a backslash. |
| .SH RETURN VALUE |
| The |
| .BR getmntent () |
| and |
| .BR getmntent_r () |
| functions return |
| a pointer to the |
| .I mntent |
| structure or NULL on failure. |
| .PP |
| The |
| .BR addmntent () |
| function returns 0 on success and 1 on failure. |
| .PP |
| The |
| .BR endmntent () |
| function always returns 1. |
| .PP |
| The |
| .BR hasmntopt () |
| function returns the address of the substring if |
| a match is found and NULL otherwise. |
| .SH FILES |
| .TP |
| .I /etc/fstab |
| filesystem description file |
| .TP |
| .I /etc/mtab |
| mounted filesystem description file |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .ad l |
| .nh |
| .TS |
| allbox; |
| lb lb lbx |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR setmntent (), |
| .BR endmntent (), |
| .BR hasmntopt () |
| T} Thread safety MT-Safe |
| T{ |
| .BR getmntent () |
| T} Thread safety T{ |
| MT-Unsafe race:mntentbuf locale |
| T} |
| T{ |
| .BR addmntent () |
| T} Thread safety T{ |
| MT-Safe race:stream locale |
| T} |
| T{ |
| .BR getmntent_r () |
| T} Thread safety MT-Safe locale |
| .TE |
| .hy |
| .ad |
| .sp 1 |
| .SH CONFORMING TO |
| The nonreentrant functions are from SunOS 4.1.3. |
| A routine |
| .BR getmntent_r () |
| was introduced in HP-UX 10, but it returns an |
| .IR int . |
| The prototype shown above is glibc-only. |
| .SH NOTES |
| System V also has a |
| .BR getmntent () |
| function but the calling sequence |
| differs, and the returned structure is different. |
| Under System V |
| .I /etc/mnttab |
| is used. |
| 4.4BSD and Digital UNIX have a routine |
| .BR getmntinfo (), |
| a wrapper around the system call |
| .BR getfsstat (). |
| .SH SEE ALSO |
| .BR fopen (3), |
| .BR fstab (5), |
| .BR mount (8) |