NAME Logfile::Tail::Switch - Tail a file, but switch when another file with newer name appears VERSION This document describes version 0.004 of Logfile::Tail::Switch (from Perl distribution Logfile-Tail-Switch), released on 2019-01-30. SYNOPSIS use Logfile::Tail::Switch; use Time::HiRes 'sleep'; # for subsecond sleep my $tail = Logfile::Tail::Switch->new( globs => ["/s/example.com/syslog/http_access.*.log"], # check_freq => 2, # tail_new => 0, ); # tail while (1) { my $line = $tail->getline; if (length $line) { print $line; } else { sleep 0.1; } } DESCRIPTION This class can be used to tail a file, but switch when a file of a newer name appears. For example, on an Spanel server, the webserver is configured to write to daily log files: /s//syslog/http_access.--
.log /s//syslog/https_access.--
.log So, when tailing you will need to switch to a new log file if you cross day boundary. When using this class, you specify a glob pattern of files, e.g. "/s/example.com/syslog/http_access.*.log". Then you call the "getline" method. This class will first select the newest file (via asciibetical sorting) from the glob pattern and tail it. Then, periodically (by default at most every 2 seconds) the glob pattern will be checked again. If there is one or more newer files, they will be read in full and then tail-ed, until an even newer file comes along. For example, this is the list of files in "/s/example.com/syslog" at time *t1*: http_access.2017-06-05.log.gz http_access.2017-06-06.log http_access.2017-06-07.log "http_access.2017-06-07.log" will first be tail-ed. When "http_access.2017-06-08.log" appears at time *t2*, this file will be read from start to finish then tail'ed. When "http_access.2017-06-09.log" appears the next day, that file will be read then tail'ed. And so on. PACKAGE VARIABLES $WARN_NO_MATCH Boolean, default 1. Whether to warn when the glob does not match any files. METHODS Logfile::Tail::Switch->new(%args) => obj Constructor. Known arguments: * globs => array Glob patterns. * check_freq => posint (default: 2) * tail_new => bool If set to true, then new file that appears will be tail'ed instead of read from the beginning. $tail->getline() => str Will return the next line or empty string if no new line is available. HOMEPAGE Please visit the project's homepage at . SOURCE Source repository is at . BUGS Please report any bugs or feature requests on the bugtracker website When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature. SEE ALSO File::Tail, File::Tail::Dir, IO::Tail Tie::Handle::TailSwitch tailswitch from App::tailswitch Spanel, . AUTHOR perlancar COPYRIGHT AND LICENSE This software is copyright (c) 2019, 2017 by perlancar@cpan.org. This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.