mk-fifo-split.1p man page

mk-fifo-split — Split files and pipe lines to a fifo without really splitting.


Usage: mk-fifo-split [options] [FILE ...]

mk-fifo-split splits FILE and pipes lines to a fifo. With no FILE, or when FILE is -, read standard input.

Read hugefile.txt in chunks of a million lines without physically splitting it:

mk-fifo-split --lines 1000000 hugefile.txt
while [ -e /tmp/mk-fifo-split ]; do cat /tmp/mk-fifo-split; done


The following section is included to inform users about the potential risks, whether known or unknown, of using this tool. The two main categories of risks are those created by the nature of the tool (e.g. read-only tools vs. read-write tools) and those created by bugs.

mk-fifo-split creates and/or deletes the "--fifo" file. Otherwise, no other files are modified, and it merely reads lines from the file given on the command-line. It should be very low-risk.

At the time of this release, we know of no bugs that could cause serious harm to users.

The authoritative source for updated information is always the online issue tracking system. Issues that affect this tool will be marked as such. You can see a list of such issues at the following URL: <…>.

See also "Bugs" for more information on filing bugs and getting help.


mk-fifo-split lets you read from a file as though it contains only some of the lines in the file. When you read from it again, it contains the next set of lines; when you have gone all the way through it, the file disappears. This works only on Unix-like operating systems.

You can specify multiple files on the command line. If you don't specify any, or if you use the special filename "-", lines are read from standard input.


This tool accepts additional command-line arguments. Refer to the "Synopsis" and usage information for details.

type: Array

Read this comma-separated list of config files; if specified, this must be the first option on the command line.
type: string; default: /tmp/mk-fifo-split

The name of the fifo from which the lines can be read.
Remove the fifo if it exists already, then create it again.
Show help and exit.
type: int; default: 1000

The number of lines to read in each chunk.
type: int; default: 0

Begin at the Nth line. If the argument is 0, all lines are printed to the fifo. If 1, then beginning at the first line, lines are printed (exactly the same as 0). If 2, the first line is skipped, and the 2nd and subsequent lines are printed to the fifo.
type: string

Create the given PID file. The file contains the process ID of the script. The PID file is removed when the script exits. Before starting, the script checks if the PID file already exists. If it does not, then the script creates and writes its own PID to it. If it does, then the script checks the following: if the file contains a PID and a process is running with that PID, then the script dies; or, if there is no process running with that PID, then the script overwrites the file with its own PID and starts; else, if the file contains no PID, then the script dies.
Print out statistics between chunks. The statistics are the number of chunks, the number of lines, elapsed time, and lines per second overall and during the last chunk.
Show version and exit.


You can download Maatkit from Google Code at <>, or you can get any of the tools easily with a command like the following:


Where "toolname" can be replaced with the name (or fragment of a name) of any of the Maatkit tools. Once downloaded, they're ready to run; no installation is needed. The first URL gets the latest released version of the tool, and the second gets the latest trunk code from Subversion.


The environment variable "MKDEBUG" enables verbose debugging output in all of the Maatkit tools:

MKDEBUG=1 mk-....

System Requirements

You need Perl, DBI, DBD::mysql, and some core packages that ought to be installed in any reasonably new version of Perl.


For a list of known bugs see <…>.

Please use Google Code Issues and Groups to report bugs or request support: <>. You can also join #maatkit on Freenode to discuss Maatkit.

Please include the complete command-line used to reproduce the problem you are seeing, the version of all MySQL servers involved, the complete output of the tool when run with "--version", and if possible, debugging output produced by running with the "MKDEBUG=1" environment variable.

Copyright, License and Warranty

This program is copyright 2007-2011 Baron Schwartz. Feedback and improvements are welcome.


This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2; OR the Perl Artistic License. On UNIX and similar systems, you can issue `man perlgpl' or `man perlartistic' to read these licenses.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.


Baron Schwartz

About Maatkit

This tool is part of Maatkit, a toolkit for power users of MySQL. Maatkit was created by Baron Schwartz; Baron and Daniel Nichter are the primary code contributors. Both are employed by Percona. Financial support for Maatkit development is primarily provided by Percona and its clients.


This manual page documents Ver 1.0.7 Distrib 7540 $Revision: 7477 $.


2011-06-08 perl v5.24.0 User Contributed Perl Documentation