FSTAB(5) UNIX Programmer's Manual FSTAB(5) NAME fstab - static information about the filesystems SYNOPSIS #include DESCRIPTION The file fstab contains descriptive information about the various file systems. fstab is only read by programs, and not written; it is the duty of the system administrator to properly create and maintain this file. Each filesystem is described on a separate line; fields on each line are separated by tabs or spaces. The order of records in fstab is important because fsck(8), mount(8), and umount(8) sequentially iterate through fstab doing their thing. The first field, _f_s__s_p_e_c, describes the block special device or remote filesystem to be mounted. For filesystems of type _u_f_s, the special file name is the block special file name, and not the character special file name. If a program needs the character special file name, the program must create it by appending a ``r'' after the last ``/'' in the special file name. The second field, _f_s__f_i_l_e, describes the mount point for the filesystem. For swap partitions, this field should be specified as ``none''. The third field, _f_s__v_f_s_t_y_p_e, describes the type of the filesystem. The system currently supports only two types of filesystems: _u_f_s a local UNIX filesystem _s_w_a_p a disk partition to be used for swapping The fourth field, _f_s__m_n_t_o_p_s, describes the mount options associated with the filesystem. It is formatted as a comma separated list of options. It contains at least the type of mount (see _f_s__t_y_p_e below) plus any additional options appropriate to the filesystem type. If the option ``quotas'' is specified, the filesystem is automatically processed by the quotacheck(8) command, and user disk quotas are enabled with quotaon(8). Filesystem quotas are maintained in the file named _q_u_o_t_a_s located at the root of the associated filesystem. This restriction on the location of the quotas file is needlessly imposed by the kernel but may be lifted in the future. Thus, if the user quota file for /_t_m_p is stored in /_v_a_r/_q_u_o_t_a_s/_t_m_p._u_s_e_r, this location can be specified as: Printed 11/26/99 January 15, 1996 1 FSTAB(5) UNIX Programmer's Manual FSTAB(5) quotas=/var/quotas/tmp.user The type of the mount is extracted from the _f_s__m_n_t_o_p_s field and stored separately in the _f_s__t_y_p_e field (it is not deleted from the _f_s__m_n_t_o_p_s field). If _f_s__t_y_p_e is ``rw'' or ``ro'' then the filesystem whose name is given in the _f_s__f_i_l_e field is normally mounted read-write or read-only on the specified special file. If _f_s__t_y_p_e is ``sw'' then the special file is made available as a piece of swap space by the swapon(8) command at the end of the system reboot pro- cedure. The fields other than _f_s__s_p_e_c and _f_s__t_y_p_e are unused. If _f_s__t_y_p_e is specified as ``xx'' the entry is ignored. This is useful to show disk partitions which are currently unused. The fifth field, _f_s__f_r_e_q, is used for these filesystems by the dump(8) command to determine which filesystems need to be dumped. If the fifth field is not present, a value of zero is returned and dump(8) will assume that the filesystem does not need to be dumped. The sixth field, _f_s__p_a_s_s_n_o, is used by the fsck(8) program to determine the order in which filesystem checks are done at reboot time. The root filesystem should be specified with a _f_s__p_a_s_s_n_o of 1, and other filesystems should have a _f_s__p_a_s_s_n_o of 2. Filesystems within a drive will be checked sequentially, but filesystems on different drives will be checked at the same time to utilize parallelism available in the hardware. If the sixth field is not present or zero, a value of zero is returned and fsck(8) will assume that the filesystem does not need to be checked. #define FSTAB_RW "rw" /* read-write device */ #define FSTAB_RO "ro" /* read-only device */ #define FSTAB_SW "sw" /* swap device */ #define FSTAB_XX "xx" /* ignore totally */ struct fstab { char *fs_spec; /* block special device name */ char *fs_file; /* filesystem path prefix */ char *fs_vfstype; /* type of filesystem */ char *fs_mntops; /* comma separated mount options */ char *fs_type; /* rw, ro, sw, or xx */ int fs_freq; /* dump frequency, in days */ int fs_passno; /* pass number on parallel dump */ }; The proper way to read records from _f_s_t_a_b is to use the rou- tines getfsent(3), getfsspec(3), getfstype(3), and getfs- file(3). Printed 11/26/99 January 15, 1996 2 FSTAB(5) UNIX Programmer's Manual FSTAB(5) FILES /_e_t_c/_f_s_t_a_b The file fstab resides in /_e_t_c. SEE ALSO getfsent(3) HISTORY The fstab file format appeared in 4.0BSD. Printed 11/26/99 January 15, 1996 3