The LEGENDARY grep command

the man page starts as follows...
 
SYNOPSIS
       grep [OPTIONS] PATTERN [FILE...]
       grep [OPTIONS] [-e PATTERN | -f FILE] [FILE...]

DESCRIPTION
       grep  searches  the named input FILEs (or standard input if no files are named, or if a single hyphen-minus (-) is given as file name) for lines containing a match to the given PATTERN.  By default, grep prints the matching lines.

       In addition, two variant programs egrep and fgrep are available.  egrep is the same as  grep -E.   fgrep  is  the  same  as grep -F.   Direct  invocation as either egrep or fgrep is deprecated, but is provided to allow historical applications that rely on them to run unmodified.
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The following are some practical uses of grep from my own experience  and some sourced from the net.

1. Search file contents

Search for the word PAGE (case sensitive) in the file application.xml;
$grep "PAGE" /opt/tomcat7/webapps.labs/primetest/WEB-INF/configs/application.xml

For case insensitive match use the -i switch as follows;

$grep -i "PAGE" /opt/tomcat7/webapps.labs/primetest/WEB-INF/configs/application.xml

2. Search inside a directory

Search for the word drvierClassName inside the directory META-INF

$ grep -R "driverClassName" META-INF/

You will see result on a separate line preceded by the name of the file in which it was found.

3. Find whole words only

When you search for class, grep will match class, className etc.

$ grep -w "class" WEB-INF/context.xml

4. Multiple word search

Use the egrep command as follows:
$ egrep -w 'word1|word2' /path/to/file

5. Count occurences

The grep can report the number of times that the pattern has been matched for each file using -c (count) switch:

$ grep -R -c "driverClassName" META-INF/

6. Show line numbers

Pass the -n switch to precede each line of output with the number of the line in the text file from which it was obtained:

$ grep -R -n "driverClassName" META-INF/

7. Names of matching files only

Use the -l (list) switch as follows;

$ grep -R -l "driverClassName" META-INF/


8. Grep invert match

You can use -v option to print inverts the match; that is, it matches only those lines that do not contain the given word. For example print all line that do not contain the word bar:

$ grep -v bar /path/to/file

NB: for coloured output (if not on by default) you can add --color=auto to your grep command

Other options:

• -A x or -B x (where x is a number) --- display “x” lines After or Before the section where the particular word is found.

Programaticaly Creating Primefaces DataExporter

The following is a utility method that creates a single HtmlCommandLink(h:commandLink NOT p:commandLink) that exports to PDF.

NB: please not that DataExporter is an ActionListener and not a UIComponent !

Modify the id and target variables accordingly

public static HtmlCommandLink createExportCommand(XMLElement wd){

    FacesContext fc = FacesContext.getCurrentInstance();
    Application application = fc.getApplication();
    ExpressionFactory ef = application.getExpressionFactory();
    ELContext elc = fc.getELContext();

    String table_id = "dt_mn_" + wd.getAttribute("key","x") + "_"  +    wd.getAttribute("keyfield","kf"); //id of parent datatable


          HtmlCommandLink command = new HtmlCommandLink();
          command.setId("cmd_pdf_" + table_id);
          command.setValue("PDF");
          command.setTitle("Click to Export");
          //command.addActionListener(new DataExporter(table.getId(),"pdf","Export","false","false","","utf-8",null,null));

          ValueExpression target = ef.createValueExpression(elc, ("mainForm:"+table_id), String.class);
          ValueExpression type = ef.createValueExpression(elc, "pdf", String.class);
          ValueExpression fileName = ef.createValueExpression(elc, "Export", String.class);
          ValueExpression pageOnly = ef.createValueExpression(elc, "true", String.class);
          ValueExpression selectionOnly = ef.createValueExpression(elc, "false", String.class);
          ValueExpression exludeColumns = ef.createValueExpression(elc, "", String.class);
          ValueExpression encoding = ef.createValueExpression(elc, "CP1252", String.class);
          MethodExpression preProcessor = FacesAccessor.createMethodExpression("#{eventManager.preProcessor}",Void.class, new Class[2]);
          MethodExpression postProcessor = FacesAccessor.createMethodExpression("#{eventManager.postProcessor}",Void.class, new Class[2]);

          DataExporter exporter = new DataExporter(target,type,fileName,pageOnly,selectionOnly,exludeColumns,encoding,null,null);

          command.addActionListener(exporter);
       // }

    return command;
      }

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Stack

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Primefaces 3.3

Tomcat 7

JSF 2.0