Stephen G. Miano > MultiTail-0.5 > MultiTail

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NAME ^

  MultiTail - Tail multiple files for Unix systems

SYNOPSIS ^

  use File::MultiTail;

DESCRIPTION ^

 This perl library uses perl5 objects to make it easy to
 tail a dynamic list of files and match/except lines using full
 regular expressions.

File::MultiTail;

        will tail multiple files and return the records 
        read to a Data Structure. The Data Structure can 
        be processed by MultiTail functions

The files specified are processed in accordance with the following rules:

Note: File devices and inode number uniquely identify each entry in the UNIX filesystem. If the stat() command shows them to be the same, then only one will be used. Windows NT filesystem NTFS does not allow links so I don't check for links on NT.

(1) Files that exist at program start time will be positioned to Object attribute "NumLines" before input.

(2) Files that become available subsequently will be read from the beginning. Attribute ScanForFiles must be set to True (>=1) for the option.

(3) If a file that has been selected as per rules 1 or 2 is deleted or truncated input will continue until end-of-file is reached before the file is closed.

(4) If a file is deleted and it is recreated it is treated as a new file, will be read from the beginning

(5) To conserve file descriptors, files that are selected for input are not actually opened until data is present beyond the input point selected. For example, if a file exists when ptail starts, ptail will determine the file mtime at that time and only open the file when the mtime increases.

    Note: mtime = Time when data was last modified. Changed by  the
                  following functions: creat, mknod, pipe, utime,
                  and write.

(6) If an opened file has not been updated for MultiTail Object attribute "MaxAge" minutes it will be closed. It will be reopened if it is later updated.

(7) Since MultiTail is OO you can alway change its attributes. If you change the list of file to be tailed (Files attribute) the attribute ScanForFiles will set to true and all dir and files ilists will be check for new files.

METHODS ^

1)

new

Creating a new PTAIL object

$tail = File::MultiTail->new( OutputPrefix => 'tf', RemoveDuplicate => $True, Files => ['/var/log','/var/adm/*.log'] );

Or

$tail = File::MultiTail->new; $tail->Files(['/var/log','/var/adm/*.log']); $tail->RemoveDuplicate($True);

    class/object method takes arguments ( All have defaults )
    and returning a reference to a newly created MultiTail object.

    File     :  File attribute accepts file names that includes 
        both explicit  file/dir  names  and  file/dir expressions.
        Duplicate  file  paths  are rejected, along with non-duplicate 
   names  that  resolve to  a  device/inode combination that is 
        currently being read. NT file name must start with drive letter
   or //. 
 
    Pattern  :  Arguments can be a file name or an array of patterns
        Stores in object attribute  "LineArray" all lines
        that contain the patterns
        (Default is *)

    ExceptPattern : Arguments can be a file name or an array of patterns
        Stores in object attribute  "LineArray" all lines except
        those that contain the patterns
        (Default is *)

    MaxAge  : Maximum time in minute that an open file will be held open
        without an update.
        (Default is 10 minute)

    NumLines : Files that exist at MultiTail start time will have up to
        NumLines lines from the end of file displayed. 
        Similar to tail -NumLines.  
        (Default is 10)

    Fuction  : Reference to a function that will be run by the MultiTail
        object.
        MultiTail object will pass a ref array of all the lines read from
        the files and passed through any filters you set in the object
                 to the function.
        0 = (Default) No Fuction

    ScanForFiles : Maximum time in minute before Read will scan for new
                                 files.
        If you change the attribute "Files" with fuction update_attribute
        the next Read will scan for new files.
        0 = (Default) Off 

    RemoveDuplicate : Removes all duplicate lines from LineArray
        0 = (Default) Off
        1 = On

        : Turn Debuging messages on for MultiTail.pm.
        0 = (Default) Off
        1 = On

    OutputPrefix : Determines the prefix applied to each output record.
        Output records are store in MultiTail object attribute "LineArray"
        The prefix is separated from the record by ': '.
        Prefixes supported are:
                       p  : path name of the input file
                       f  : file name of the input file
                       t  : time in HHMMSS
                       tg : time in HHMMSS GMT
                       tc : time in MM/DD/YYYY HH:MM:SS
                       pt : path and time
                       ptg: path and time GMT
                       ptc: path and time complete
                       ft : file and time
                       ftg: file and time GMT
                       ftc: file and time complete
                       tp : time and path
                       tpg: time and path GMT
                       tpc: time complete and path
                       tf : time and file
                       tfg: time and file GMT
                       tfc: time complete and file
        0 = (Default) No prefix
        GMT = Greenwich time ZONE

 Exit Codes

         1001 - MaxAge is less the zero
         1002 - NumLines is less the zero
         1003 - OutputPrefix must one ( )
         1004 - Pattern must is not a file or ARRAY
         1005 - ExceptPattern is not a file or ARRAY
         1006 - Debug is not 0 or 1
         1007 - ScanForFiles is less the zero
         1008 - RemoveDuplicate is not 0 or 1
         1009 - Function is not ref to fuction
         1010 - File attribute not set
read

Read all new data from file

$tail->read

Read all new date from tailed files and return new lines as part of the Data Structure (MultiTail Object attribute LineArray)

print

Print all line contained in MultiTail Object attribute LineArray

$tail->print

update_attribute

Allow you to Update (Change) any MultiTail Object attribute

$tail->update_attribute( Files => ["/var/log","/var/adm","/home/nnysgm/logwatcher/foo*"], ExceptPattern => /home/nnysgm/ExceptPattern.txt, RemoveDuplicate => $True );

This changes the Files, ExceptPattern and RemoveDuplicate attributes for the Object $tail.

New files will be scanned for during next Read if "Files" attribute is changed.

Also you can use supplied methods to set attribute values.

$tail->RemoveDuplicate($True); $tail->NumLines(100);

version

Return version number on PTAIL package

$tail->version

debug

Toggle the debug switch for MultiTail package

$tail->debug

        There are a number of  function in the MultiTail.pm module.
                
                o printstat :
                        Print out stat output for each file.
                o printfilestates :
                        Print out All file states. 
                        (See note in MultiTail.pm for function OpenUpdateFiles)
                o printpat :
                        Print out lines from pattern file array.
                o printexceptpat :
                        Print out line from pattern file except array.
close_all_files

Closes all file that are being tailed

$tail->close_all_files

EXAMPLE ^

1) use File::MultiTail;

        $tail1=File::MultiTail->new (  OutputPrefix => "f", 
                      Debug => "$True", 
                      Files => ["/var/adm/messages"]
        );

        while(1) {
                $tail1->read;
                #
                $tail1->print;
                sleep 10;
        }

$tail1=MultiTail->new : Create new ptail object

- Files => Tail file /var/adm/messages

- OutputPrefix => Prepend the name of the file beginning of each line in object attribute "LineArray"

$tail1->read : Read all line from files

$tail1->print : Print all line in object attribute "LineArray";

2) use File::MultiTail;

        $tail1=File::MultiTail->new (  OutputPrefix => "tf", 
                      Pattern => "/home/nnysgm/logwatcher/pattern",
                      ExceptPattern => "/home/nnysgm/logwatcher/epattern",
                      Fuction = > \&want,
            Files => ["/var/adm","/var/log/*.log"]
        );

        while(1) {
                $tail1->read;
                #
                $tail1->print;
                sleep 10;
        }
        
        sub want {
                        (your code .... );
        }

$tail1=File::MultiTail->new : Create new ptail object

- OutputPrefix => Prepend the name of the file and time to the beginning of each line in object attribute "LineArray"

- ExceptPattern => Stores in object attribute "LineArray" all lines except those that contain the patterns from file "epattern" - Pattern => Stores in object attribute "LineArray" all lines that contain the patterns from file "pattern"

- Fuction => ref to a function that will be run by MultiTail object. MultiTail object will pass a ref array to the function of all the lines read from the file and passed through any filters you set in the object.

- Files => Tail all files in dir /var/adm and all .log files dir /var/log.

$tail1->read : Read all line from files

$tail1->print : Print all line in object attribute "LineArray";

3) use File::MultiTail;

   $tail=File::MultiTail->new;

        $tail->OutputPrefix(tf);
   $tail->Fuction(\&want);
   $tail->Files(["/var/adm","/var/log/*.log"]);
  
   while(1) {
      $tail1->read;
   }
                      
   sub want {
         (your code .... );
   }         

AUTHOR ^

Stephen Miano, smiano@mindspring.com

SEE ALSO ^

perl(1).

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