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. (Check for links)
(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
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.
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
pt : path and time
ptg: path and time GMT
ft : file and time
ftg: file and time GMT
tp : time and path
tpg: time and path GMT
tf : time and file
tfg: time and file GMT
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, stevem@esm.com
SEE ALSO
perl(1).