pgmhist

Display the histogram for human reading

$ pgmhist [path/to/image.pgm]

$ pgmhist [[-me|-median]] [path/to/image.pgm]

$ pgmhist [[-qua|-quartile]] [path/to/image.pgm]

$ pgmhist [[-f|-forensic]] [path/to/image.pgm]

$ pgmhist [[-ma|-machine]] [path/to/image.pgm]

pgmhist [OPTIONS] [PROGRAM_NAME]

-u, --user user_id
    Filters the program history to display only entries related to a specific user or user_id.

-p, --program program_name
    Shows the execution history for a particular program_name, ignoring other programs.

-t, --time duration
    Filters entries by a time duration, such as '1 day', '2 weeks', 'last 3 hours', or a specific timestamp range (e.g., 'YYYY-MM-DD HH:MM:SS to YYYY-MM-DD HH:MM:SS').

-n, --lines number
    Limits the output to the last number of program execution entries.

-v, --verbose
    Displays verbose details for each execution entry, potentially including process ID (PID), parent process ID (PPID), exit status, and full command-line arguments.

-s, --source type
    Specifies the data source to query. Possible values could include 'shell' (for shell history), 'audit' (for system audit logs), or 'acct' (for process accounting data).

-o, --output format
    Formats the output in a specified format, such as 'json', 'csv', or 'plain' (default).

--system-wide
    Displays history for all users and system processes (requires appropriate permissions).

The command pgmhist (Program History) is a hypothetical or non-standard Linux utility designed to display a comprehensive history of program executions on a system. It would aggregate information from various sources to provide insights into which programs were run, by whom, when, and possibly with what arguments. This command would be invaluable for system auditing, security analysis, troubleshooting, and understanding user activity. Unlike simple shell history, pgmhist aims to provide a system-wide view, potentially drawing data from process accounting, system audit logs, and shell history files to offer a unified timeline of program usage. Its utility lies in offering a detailed retrospective on system and user behavior, allowing administrators to track software usage patterns, identify unauthorized program executions, or diagnose issues by reviewing past command invocations.

This command, pgmhist, is not a standard Linux utility and is not distributed with major Linux distributions. Its functionality and existence are hypothetical in a general Linux context. Any implementation of such a command would be custom-built and would rely heavily on the availability and configuration of underlying system logging mechanisms, such as `auditd` rules for `execve` syscalls, process accounting (`acct`), and potentially a persistent storage solution (like a database) to efficiently store and query historical data. Therefore, the behavior described is conceptual and would depend entirely on a specific system's custom setup. Without proper configuration of data sources, this command would not be able to retrieve any information.

A robust pgmhist implementation would require sophisticated data aggregation. It would ideally pull information from diverse sources:

1. Shell History: Files like ~/.bash_history, ~/.zsh_history for user-executed commands.
2. Audit Logs: System-wide logs generated by auditd (e.g., /var/log/audit/audit.log), configured to capture execve syscalls, providing details on all program executions, including those not run via an interactive shell.
3. Process Accounting: Files like /var/account/pacct, which record summary information about completed processes, including user, command, start/end times, and resource usage.

Combining these diverse data streams, filtering out redundant entries, and presenting them in a coherent chronological order would be a primary challenge for this command.

Developing a reliable pgmhist would involve several significant technical considerations. Firstly, it would need efficient parsers for various log formats and potentially a backend database (e.g., SQLite, PostgreSQL, or a specialized time-series database) to store and index the large volumes of historical data for quick querying. Secondly, handling permissions and security is critical; accessing system-wide audit and accounting logs typically requires root privileges, and the command itself would need to be designed securely. Lastly, performance would be a key concern, as querying vast historical datasets can be resource-intensive. Incremental updates, caching, and optimized indexing would be necessary for practical usage.

As pgmhist is not a standard or widely recognized Linux command, there is no official development or usage history. Conceptually, a command named 'program history' could emerge from various needs within system administration and security. For instance, in environments requiring strict compliance (e.g., PCI DSS, HIPAA), the ability to audit program execution is crucial. Similarly, in incident response scenarios, understanding what programs were run by an attacker is vital. It might also find use in performance monitoring or resource management, by analyzing the frequency and duration of program usage. Such a utility would likely be either a custom script developed by system administrators for specific organizational needs or a component of a larger proprietary system management or security information and event management (SIEM) solution, rather than a standalone, general-purpose command.

history(1), last(1), auditd(8), ausearch(8), acct(5), ps(1)