IntroWhat is System::ProcWatch?System::ProcWatch is a small collection of classes to ease monitoring of system processes based on the Unix program procps (ps). To use System::ProcWatch you simply have to define a ruleset on which based System::ProcWatch operates. A rule (or job, watch) defines what actions should happen if a condition evaluates to true. To be continued... Shell ScriptsYou can use System::ProcWatch out of the box, by utilizing the shipped shell scripts procwatch and procwatch-lint. procwatchThe procwatch command is meant to be used for system diagnosis - run as daemon or by cron. The usage is best described by the output of procwatch -h:
procwatch-lintThe procwatch-lint is meant to validate procwatchs configurtation files written in XML by utilizing XML::DTD::XmlValidator. Once again synopsis is best described by the output of procwatch-lint -h:
ConfigurationThere are three methods to configure your System::ProcWatch application:
Xml string/fileConfiguring System::ProcWatch by XML is the preferred way. It is as simple as powerful. Ruleset: The Root ElementThe root element of an XML configuration file is the procwatch element. It has one implicit attribute, the version attribute, set to "1.0". The procwatch element symbolizes our ruleset, and the childs of the root are our rules. Rules: The Childs of the RootThe direct descendants of the root element procwatch, are the watch elements, which can occur 1 time or more often. The watch element has one required attribute, the name attribute, which gives the watch (or job, rule) a descriptive name like "httpd-count". Each watch element symbolizes a single rule, containing a regular expression to search for, one or more conditions to evaluate and one or more actions to be taken. Rule Element: patternThe pattern element describes the perl compatible regular expression which should be evaluated against a column of the output of ps. There is one required attribute, the match attribute, defining the column name of the output of ps in lowercase like "command" or "vsz". This makes System::ProcWatch highliy versatile and should make it usable with any platforms procps program. The pattern elements content solely consits of the perl compatible regular expression to match against the column defined in the match attribute. The PCRE MUST contain the start and end delimiter and MAY contain any PCRE modifiers. Example: <pattern match="command">/sbin\/httpd/</pattern> Rule Element: conditionThe condition element defines conditions that MUST evaluate to TRUE at all so that later defined actions will be executed. The condition element has one required and one optional attribute, the required one being type, which MUST be one of "presence" or "attr", and the optional one being attr. However, if the type attribute equals to "attr" the attr attribute MUST be present. The attr attribute represents a column of procps' output like "user" or "%mem". ConditionsDependent on the content of the type attribute, syntax and behavior of the condition element differ. A condition with type "presence" MAY be empty, thus always evaluating to true. Child Elements of condition may be:
You may combine them to define for instance a range from min to max. Rule Element: executeThe execute element defines actions that should be taken if the condition applies. It has one required attribute, the type attribute, which MUST equal to one of "shell" or "php". Obviously the content of the execute element is executed either on the shell through shell_exec() or directly in PHP through eval(). The execute element MAY occur any times. There are some special variables that will automagically be available in execute statements:
Example XML configuration file
INI fileConfiguring by INI file is effectively the same except that only executes of type "shell" can be defined. Example INI configuration file
Example PHP configuration array
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