bart_rules - bart rules file
The bart_rules file is a text file that is used by the bart(8) command. The rules file determines which files to validate and which file attributes of those files to ignore.
Some lines are ignored by the manifest comparison tool. Ignored lines include blank lines, lines that consist only of white space, and comments that begin with #.
The rules file supports three directives: CHECK, IGNORE, and a subtree directive, which is an absolute path name and optional pattern matching modifiers. Each CHECK, IGNORE, and subtree directive must be on a separate line. Bart supports continuation of long lines using a backslash (\). The rules file uses the directives to create logical blocks.
The syntax for the rules file is as follows:
[IGNORE attribute...]* [CHECK] [attribute...]* subtree1 [pattern...]* [IGNORE attribute...]* [CHECK] [attribute...]* subtree2 [pattern...]* subtree3 [pattern...]* subtree4 [pattern...]* [IGNORE attribute...]* [CHECK] [attribute...]* ...
Rule blocks are composed of statements that are created by using directives and arguments.
There are three types of blocks:
The first block in the file. The block is considered “global” if it specifies CHECK and IGNORE statements, but no previous subtree statement. A global block pertains to all subsequent blocks.
A block that specifies CHECK and IGNORE statements as well as a subtree directive. The rules in this block pertain to files and directories found in the specified subtree.
A block that contains a null CHECK statement, no arguments. This block inherits the global CHECK statements and IGNORE statements.
The order in which CHECK and IGNORE statements appear in blocks is important. The bart command processes CHECK and IGNORE statements in the order in which they are read, with later statements overriding earlier statements.
Subtree specifications must appear one per line. Each specification must begin with an absolute path name. Optionally, each specification can be followed by pattern-matching modifiers.
When a file system being tracked belongs to more than one subtree directive, bart performs the following resolution steps:
Applies the CHECK and IGNORE statements set in the global block. Note that all CHECK and IGNORE statements are processed in order.
Finds the last subtree directive that matches the file.
Processes the CHECK and IGNORE statements that belong to the last matching subtree directive. These statements are processed in the order in which they are read, overriding global settings.
There are two types of pattern matching modifiers:
For a given subtree directive, pattern matching modifiers are logically ANDed all together and with the subtree. In other words, for an entry to match the subtree block rule, it must match the subtree directive and ALL pattern matching modifiers. Therefore, it usually makes little sense to specify more than one positive pattern matching modifier for the given subtree block rule. Patterns have the following syntax:
Wildcards are permitted for both the subtree and pattern matching modifiers.
The exclamation point (!) character represents logical NOT.
A pattern that terminates with a slash is a subtree. The absence of a slash indicates that the pattern is not a directory. The subtree itself does not require an end slash.
For example, the following subtree example includes the contents of /home/nickiso/src except for object files, core files, and all of the SCCS subtrees. Note that directory names that terminate with .o and directories named core are not excluded because the patterns specified do not terminate with /.
/home/nickiso/src !*.o !core !SCCS/ CHECK all
No possible entry can match the following subtree block rule because the two specified pattern matching modifiers are disjunct:
/home/nickiso/src *.o core CHECK all
Group multiple subtree directives together. Such subtree directives are logically ORed together.
/home/nickiso/src !*.o !core /home/nickiso/Mail /home/nickiso/docs *.sdw CHECK all IGNORE mtime lnmtime dirmtime
The files included in the previous example are as follows:
Everything under /home/nickiso/src except for *.o and core files
Everything under /home/nickiso/Mail
All files under /home/nickiso/docs that end in *.sdw
For these files, all attributes are checked except for modification times.
The bart command uses CHECK and IGNORE statements to define which attributes to track or ignore. Each attribute has an associated keyword.
The attribute keywords are as follows:
ACL attributes for the file. For a file with ACL attributes, this field contains the output from acltotext().
Checksum value of the file. This attribute is only specified for regular files. If you turn off context checking or if checksums cannot be computed, the value of this field is –.
Destination of a symbolic link.
Value of the device node. This attribute is for character device files and block device files only.
Modification time in seconds since 00:00:00 UTC, January 1, 1970 for directories.
Numerical group ID of the owner of this entry.
Creation time for links.
Octal number that represents the permissions of the file.
Modification time in seconds since 00:00:00 UTC, January 1, 1970 for files.
File size in bytes.
Type of file.
Numerical user ID of the owner of this entry.
The following is a sample rules file:
# Global rules, track everything except dirmtime. CHECK all IGNORE dirmtime # The files in /data* are expected to change, so don't bother # tracking the attributes expected to change. # Furthermore, by specifying "IGNORE contents", you save # time and resources. /data* IGNORE contents mtime size /home/nickiso f* bar/ IGNORE acl # For /usr, apply the global rules. /usr CHECK # Note: Since /usr/tmp follows the /usr block, the /usr/tmp # subtree is subjected to the "IGNORE all". /usr/tmp /home/nickiso *.o /home/nickiso core /home/nickiso/proto IGNORE all
Based on the sample rules file, the following files are catalogued into the manifests:
Files under /data* and /usr subtree.
Files under /home/nickiso subtree beginning with f and files under /home/nickiso/bar subtree.
All .o and core files under /home/nickiso , as well as the /home/nickiso/proto and /usr/tmp subtrees.
When the same rules file is used again when comparing the manifests, then the following files and attributes are tracked:
All attributes, except for dirmtime, mtime, size, and contents, are tracked for files under the /data* subtrees.
All files and all their attributes (except dirmtime ) under the /usr subtree, except for /usr/tmp, are tracked by using the global rules.
If the /home/nickiso/foo.c file exists, its attributes, except for acl and dirmtime , are tracked.
All .o and core files under /home/nickiso, as well as the /home/nickiso/proto and /usr/tmp subtrees, are ignored.
If the /home/nickiso/bar/foo.o file exists, it is ignored because it is subject to the last block.