+.SH ENVIRONMENT VARIABLES
+The
+.B fsck
+program's behavior is affected by the following environment variables:
+.TP
+.B FSCK_FORCE_ALL_PARALLEL
+If this environment variable is set,
+.B fsck
+will attempt to run all of the specified filesystems in parallel,
+regardless of whether the filesystems appear to be on the same
+device. (This is useful for RAID systems or high-end storage systems
+such as those sold by companies such as IBM or EMC.)
+.TP
+.B FSCK_MAX_INST
+This environment variable will limit the maximum number of file system
+checkers that can be running at one time. This allows configurations
+which have a large number of disks to avoid
+.B fsck
+starting too many file system checkers at once, which might overload
+CPU and memory resources available on the system. If this value is
+zero, then an unlimited number of processes can be spawned. This is
+currently the default, but future versions of
+.B fsck
+may attempt to automatically determine how many file system checks can
+be run based on gathering accounting data from the operating system.
+.TP
+.B PATH
+The
+.B PATH
+environment variable is used to find file system checkers. A set of
+system directories are searched first:
+.BR /sbin ,
+.BR /sbin/fs.d ,
+.BR /sbin/fs ,
+.BR /etc/fs ,
+and
+.BR /etc .
+Then the set of directories found in the
+.B PATH
+environment are searched.
+.TP
+.B FSTAB_FILE
+This environment variable allows the system administrator
+to override the standard location of the
+.B /etc/fstab
+file. It is also useful for developers who are testing
+.BR fsck .