dirsplit

dirsplit <source_directory> <destination_directory_prefix> [OPTIONS]

<source_directory>
    The path to the source directory whose contents (files and subdirectories) are to be split.

<destination_directory_prefix>
    The base path where new subdirectories will be created. For example, if 'split_data/' is provided, subdirectories like 'split_data/001/', 'split_data/002/' will be created.

--items <N>
    Splits the source directory's contents such that each new subdirectory contains approximately N files/items. This option is mutually exclusive with --dirs.

--dirs <M>
    Splits the source directory's contents evenly into M new subdirectories. This option is mutually exclusive with --items.

--type <action>
    Specifies the action to perform on the files: 'move' (default) to move files, 'copy' to copy files, or 'link' to create symbolic links. Be cautious with 'move' as it changes file paths.

--dry-run
    Performs a simulated run, showing which files would be moved/copied/linked and where, without making any actual changes to the filesystem. Highly recommended for testing.

--verbose
    Enables verbose output, providing more detailed information about the splitting process as it happens.

--help
    Displays a help message with usage instructions and available options.

The command dirsplit is not a standard, pre-installed Linux utility found in most distributions. Instead, it typically refers to a custom script or a user-contributed tool designed to address the challenge of managing directories containing an excessively large number of files. Such scenarios can lead to performance issues with file system operations (like ls, find, backups) and can sometimes hit filesystem inode limits or practical manageability thresholds.

A common implementation of dirsplit works by taking all files and/or subdirectories from a specified source directory and distributing them into a new set of subdirectories within a destination path. The distribution can be based on various criteria, such as limiting the number of items per new subdirectory, or by distributing items evenly across a pre-defined number of new subdirectories. The operation can typically involve moving, copying, or symbolically linking the original files to their new locations, effectively 'sharding' the large directory's contents.

dirsplit is NOT a standard Linux command. Implementations can vary significantly between different scripts or user-contributed versions. Always verify the script's source and functionality before execution. Using the --type move option will permanently change the paths of your files; ensure you have backups. Operations on extremely large directories can be time and resource-intensive. Be aware that splitting a directory's contents breaks the original logical grouping, which might affect applications or scripts expecting files at their original paths.

Reasons for using dirsplit often include:
Improving File System Performance: Many file systems and utilities perform poorly with directories containing hundreds of thousands or millions of files. Splitting them can significantly speed up operations like listing, searching, or traversing.
Backup and Archiving: Splitting large directories into smaller, manageable chunks can simplify backup strategies, allowing for more granular and faster incremental backups.
Data Distribution: For distributed systems or transferring data, splitting a monolithic directory can make it easier to distribute content across multiple storage nodes or transfer archives more efficiently.
Overcoming Filesystem Limits: Some older filesystems or specific configurations might have practical limits on the number of entries in a single directory, which dirsplit can help circumvent.

A typical dirsplit script internally uses commands like find to list files, mkdir to create new subdirectories, and then mv, cp, or ln to move/copy/link files. It usually involves iterating through the source directory and assigning files sequentially or randomly to the target subdirectories based on the specified splitting logic. The naming convention for new subdirectories often involves sequential numbers (e.g., '001', '002', '003').

Unlike standard Unix utilities with defined release histories, dirsplit does not have a single, official development history. The need to split large directories arose with the growth of data storage and the limitations of certain filesystems or backup tools when dealing with massive file counts in a single directory. As such, various users and administrators independently developed scripts (often in Bash, Python, Perl) to perform this task. These scripts are typically shared within communities or developed in-house, making dirsplit more of a common solution pattern than a specific command with a unified lineage.

find(1), xargs(1), mv(1), cp(1), ln(1), rsync(1)