---
name: "Paranoid::IO::Lockfile"
section: "3pm"
platform: "linux"
package: "libparanoid-perl"
version: "2.10-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Paranoid::IO::Lockfile"
---

# Paranoid::IO::Lockfile(3pm)

Paranoid Lockfile support

## NAME

Paranoid::IO::Lockfile - Paranoid Lockfile support

## VERSION

`$Id:` lib/Paranoid/IO/Lockfile.pm, 2.10 2022/03/08 00:01:04 acorliss Exp $

## SYNOPSIS

```
  use Paranoid::IO::Lockfile;
  use Fcntl qw(:flock);  # only needed if you use plock in lieu
                         # of the other functions
  $rv = plock($lockfile);
  $rv = plock($lockfile, LOCK_SH | LOCK_NB);
  $rv = plock($lockfile, LOCK_SH | LOCK_NB, $mode);
  $rv = pexclock($lockfile);
  $rv = pshlock($lockfile);
  $rv = punlock($lockfile);
```

## DESCRIPTION

This module provides convenience functions for using a lockfile to coordinate multi-process activities.  While basically just a thin wrapper for Paranoid::IO functions it removes the small tedium of having to perform the multiple opens required to ensure all processes are working off the same files while avoiding race conditions.

## IMPORT LISTS

This module exports the following symbols by default:

```
    plock pexclock pshlock punlock
```

The following specialized import lists also exist:

```
    List        Members
    --------------------------------------------------------
    all         @defaults
```

## SUBROUTINES/METHODS

### plock

```
  $rv = plock($filename);
  $rv = plock($filename, LOCK_EX);
  $rv = plock($filename, LOCK_EX, 0666);
```

Creates or opens the requested file while applying the lock condition.  The lock type defaults to **LOCK\_EX** if omitted, while the file permissions default to **0660**.  As always, umask applies.

There is one scenario in which one would want to use *plock* in lieu of *pexclock*, etc:  if you wish to perform non-blocking lock attempts.  All convenience functions are blocking.

### pexclock

```
  $rv = pexclock($filename);
  $rv = pexclock($filename, $mode);
```

A wrapper for **plock($filename, LOCK\_EX)**.

### pshlock

```
  $rv = pshlock($filename);
  $rv = pshlock($filename, $mode);
```

A wrapper for **plock($filename, LOCK\_SH)**.

### punlock

```
  $rv = punlock($filename);
  $rv = punlock($filename, $mode);
```

A wrapper for **plock($filename, LOCK\_UN)**.  This does not close the open  file handle to the lock file.  For that you need to call Paranoid::IO's *pclose* function.

## DEPENDENCIES

- o

  Fcntl

- o

  Paranoid

- o

  Paranoid::Debug

- o

  Paranoid::IO

## BUGS AND LIMITATIONS

## AUTHOR

Arthur Corliss (corliss@digitalmages.com)

## LICENSE AND COPYRIGHT

This software is free software.  Similar to Perl, you can redistribute it and/or modify it under the terms of either:

```
  a)     the GNU General Public License
         <https://www.gnu.org/licenses/gpl-1.0.html> as published by the
         Free Software Foundation <http://www.fsf.org/>; either version 1
         <https://www.gnu.org/licenses/gpl-1.0.html>, or any later version
         <https://www.gnu.org/licenses/license-list.html#GNUGPL>, or
  b)     the Artistic License 2.0
         <https://opensource.org/licenses/Artistic-2.0>,
```

subject to the following additional term:  No trademark rights to "Paranoid" have been or are conveyed under any of the above licenses. However, "Paranoid" may be used fairly to describe this unmodified software, in good faith, but not as a trademark.

(c) 2005 - 2020, Arthur Corliss (corliss@digitalmages.com) (tm) 2008 - 2020, Paranoid Inc. (www.paranoid.com)