Using Pipelines to Select Classes

Using the Unix find command to select the class files to process, provides infinite flexibility.

You can specify a range of modification times for the files. As an example, the following command will print the metrics of the class files modified during the last week.
```
find build -name '*.class' -mtime -7 -print | java -jar /usr/local/lib/ckjm.jar
```
You can filter out specific patterns, either with the GNU find's regular expression options, or by piping its results through grep. As an example, the following command will not print metrics for internal classes (their name contains a $ character).
```
find build -name '*.class' | fgrep -v '$' | java -jar /usr/local/lib/ckjm.jar
```
You process contents from several directories. As an example, the following command will process the class files located in the build and lib directories.
```
find build lib -name '*.class' -print | java -jar /usr/local/lib/ckjm.jar
```
You generate the list of class files, by processing the list of contents of a jar file. The following example will calculate the metrics for all class files located in the file ant.jar (the sed step prints only the lines ending in .class, replacing the beginning of the line with the name of the jar file, ant.jar. .
```
jar tf ant.jar |
sed -n '/\.class$/s/^/ant.jar /p' |
java -jar /usr/local/lib/ckjm.jar
```
You can also combine the above patterns (and more) into more sophisticated file location and selection options. The following example, will process the classes of all jar files located in the lib directory.
```
for i in lib/*.jar
do
        jar tf $i |
        sed -n "/\.class$/s,^,$i ,p"
done |
java -jar /usr/java/ckjm-1.3/build/ckjm-1.3.jar
```
(Replace the sequence /usr/java/ckjm-1.3/build/ckjm-1.3.jar with the actual path and filename of the ckjm version you are using.)

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