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<?xml version="1.0" encoding="utf-8"?>
<!--
Written by Michael Tokarev <mjt@tls.msk.ru>
Public domain.
-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.4//EN"
"file:///usr/share/xml/docbook/schema/dtd/4.4/docbookx.dtd"
[]>
<refentry>
<refentryinfo>
<address>
<email>mjt@tls.msk.ru</email>
</address>
<author>
<firstname>Michael</firstname>
<surname>Tokarev</surname>
</author>
<date>2007-08-15</date>
</refentryinfo>
<refmeta>
<refentrytitle>lckdo</refentrytitle>
<manvolnum>1</manvolnum>
</refmeta>
<refnamediv>
<refname>lckdo</refname>
<refpurpose>run a program with a lock held</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>lckdo</command>
<arg>options</arg>
<arg choice="req">lockfile</arg>
<arg choice="req">program</arg>
<arg>arguments</arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>DESCRIPTION</title>
<para><command>lckdo</command> runs a program with a lock
held, in order to prevent multiple processes from running in
parallel. Use just like <command>nice</command> or
<command>nohup</command>.</para>
</refsect1>
<refsect1>
<title>OPTIONS</title>
<variablelist>
<varlistentry>
<term><option>-w</option></term>
<listitem>
<para>If the lock is already held by another process,
wait for it to complete instead of failing
immediately.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-W {sec}</option></term>
<listitem>
<para>The same as -w but wait not more than sec
seconds.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-e</option></term>
<listitem>
<para>Execute the program directly without forking and
waiting (keeps an extra file descriptor open).</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-E {nnn}</option></term>
<listitem>
<para>Set the file descriptor number to keep open when
exec()ing (implies -e).</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-n</option></term>
<listitem>
<para>Do not create the lock file if it does not
exist.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-q</option></term>
<listitem>
<para>Produce no output if lock is already held.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-s</option></term>
<listitem>
<para>Lock in shared (read) mode.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-x</option></term>
<listitem>
<para>Lock in exclusive (write) mode (default).</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-t</option></term>
<listitem>
<para>Test for lock existence.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>EXIT STATUS</title>
<para>If the lock was successfully acquired, the return value is that
of the program invoked by <command>lckdo</command>. If the lock
couldn't be acquired, EX_TEMPFAIL is returned. If there was a problem
opening/creating or locking the lock file, EX_CANTCREAT or EX_OSERR
will be returned.</para>
</refsect1>
</refentry>
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